Vote Splitting

This is commonly known as the spoiler effect, which can discourage minor party candidacies.

Vote splitting most easily occurs in plurality voting (also called first-past-the-post) in which each voter indicates a single choice and the candidate with the most votes wins, even if the winner does not have majority support. For example, if candidate A1 receives 30% of the votes, similar candidate A2 receives another 30% of the votes, and dissimilar candidate B receives the remaining 40% of the votes, plurality voting declares candidate B as the winner, even though 60% of the voters prefer either candidate A1 or A2.

One of the main functions of political parties is to mitigate the effect of spoiler-prone voting methods by winnowing on a local level the contenders before the election. Each party nominates at most one candidate per office since each party expects to lose if they nominate more than one. This means empirical observations of the frequency of spoiled elections may not be a good measure, because they exclude relevant information from candidates who chose not to run.

Vote splitting occurs when candidates or ballot questions have similar ideologies. A spoiler candidate can draw votes from a major candidate with similar politics, thereby causing a strong opponent of both or several to win. The minor candidates causing this effect are referred to as spoilers.

The problem also exists in two-round system and instant-runoff voting, though it is reduced, because weaker spoilers are eliminated.^{[citation needed]} However, a candidate that can win head-to-head against all rivals (called a Condorcet winner) can still lose from third place in a 3-way vote split, a phenomenon known as a center squeeze. This occurred in the 2009 Burlington Vermont mayoral election and the 2022 Alaska's at-large congressional district special election.

All ranked-choice systems suffer from variations of the spoiler effect, as proven by Arrow's impossibility theorem.

Australia

In Australia, seats where vote splitting occurs are called "three-corned contests". While the vote is split in a three-cornered contest, it is not always a disadvantage as Australia uses preferential voting. However, depending on the level of government it can still act as a disadvantage due to the different forms of preferential voting used in Australia; full preferential voting (FPV) is used on a federal level and in some states and territories while optional preferential voting (OPV) is used in New South Wales. Due to this, three-cornered contests are rare in New South Wales (on both a state and federal level) as well as in the federal Senate.

Three-cornered contests generally occur with the centre-right Liberal-National Coalition. However, the frequency of these contests varies in different states and it does not occur in the Queensland, Tasmania or the two territories, due to the fact that the Nationals do not exist in the Australian Capital Territory (ACT) and they do not currently contest elections in Tasmania, while in Queensland and the Northern Territory the two Coalition parties merged to become the Liberal National Party (LNP) and the CLP, respectively. While they are rare in New South Wales, three-cornered contests do often occur in Victoria, Western Australia and South Australia.

Federal politics

 

Federally, three-cornered contests are uncommon in most seats. However, they do occur in certain regional seats. At the 2022 federal election, both Coalition parties ran candidates in four seats; two in Victoria (Division of Indi, Nicholls), one in Western Australia (Durack) and one in South Australia (Barker). The number of federal seats with three-cornered contests has dropped over the years. In fact, there was a significantly low number of three-cornered contests in 2022, even when compared to the previous federal election, which was held in 2019. In that election, both Coalition parties ran candidates in ten seats; two in New South Wales (Eden-Monaro and Gilmore), two in Victoria (Indi and Mallee), two in Western Australia (Durack and O'Connor), one in South Australia (Barker) and three in Tasmania (Bass, Braddon and Lyons).

State politics

In New South Wales (the only state where the Coalition has never been broken), three-cornered contests are rare as most Coalition voters exhaust their preferences (meaning they only number one candidate, thus being a disadvantage except in conservative strongholds on the Mid North Coast and in central and western parts of the state). However, at the 2023 state election, this phenomenon did occur in two regional seats: Port Macquarie (a conservative seat held by National-turned-Liberal MP Leslie Williams) and Wagga Wagga (a traditionally conservative seat, despite being held by independent MP Joe McGirr). In Port Macquarie, Williams was the Liberal candidate and Peta Pinson, the Mayor of the Port Macquarie-Hastings Council, was the Nationals candidate. Williams won the seat, which despite having a three-cornered contest remained a safe seat on both two-candidate-preferred (TCP) and two-party-preferred (TPP) margin. In Wagga Wagga, the Nationals candidate was Adrianna Benjamin and the Liberal candidate was Julia Ham. McGirr retained the seat with an increased TCP margin against Benjamin, although the Nationals still won the TPP count. It is unlikely that a three-cornered contest will occur in either of these seats at the next state election, which will be held in 2027.

In Victoria, three-cornered contests occur in some seats, despite the Coalition existing in Victoria (although it has previously been broken). At the 2022 state election, both Coalition parties ran candidates in five seats (Bass, Euroa, Mildura, Morwell and Shepparton). The Nationals intended to run a candidate in the Narracan, but the candidate they preselected died before the election, forcing a supplementary by-election in that seat, in which the Liberal candidate was re-elected and the Nationals did not run a candidate.

In Western Australia, three-cornered contests do commonly occur. This is due to the fact that the Coalition agreement is different in that both parties are independent of each other and each party can vote differently if they believe that their decision it is in the best interests of the people and areas they represent. The Nationals can also opt-out of Cabinet and when a Coalition government is elected, the leader of the Liberal Party becomes the state Premier, but the leader of the Nationals does not always become the Deputy Premier, unlike in New South Wales and Victoria where in the event of a Coalition government, the Liberal leader becomes the Premier and the Nationals leader becomes the Deputy Premier. For example, following the 2008 state election, which saw a Coalition government elected, the Liberal leader (Colin Barnett) became the Premier, but the Nationals leader (Brendon Grylls) did not become the Deputy Premier, an office that the deputy Liberal leader (Kim Hames) was given instead.

In South Australia, three-cornered-contests do occur in some seats, due to the absence of the Coalition. In most states, the Liberal Party holds seats in cities while the Nationals hold seats in regional, rural and remote areas, but in South Australia and Tasmania, the Nationals have limited activity and thus the Liberals hold both metropolitan and non-metropolitan seats in these states. At the 2022 state election, both the Liberals and the Nationals ran candidates in eight seats (Chaffey, Finniss, Flinders, Frome, Hammond, MacKillop, Narungga and Schubert). Due to the limited activity of the party, the Nationals finished last or close-to-last in all of these seats, even being outvoted by some minor parties and winning a statewide vote of just 0.48%, the lowest in the country on a state level (excluding states the party does not contest elections in).

In Australia, the 1918 Swan by-election saw the conservative vote split between the Country Party and Nationalist Party, which allowed the Australian Labor Party to win the seat. That led the Nationalist government to implement preferential voting in federal elections to allow Country and Nationalist voters to transfer preferences to the other party and to avoid vote splitting. Today, the Liberal Party and National Party rarely run candidates in the same seats, which are known as three-cornered contests. When three-cornered contests do occur the Labor Party would usually direct preferences to the Liberals ahead of the Nationals as they considered the Liberal Party to be less conservative than the Nationals. The 1996 Southern Highlands state by-election in New South Wales is an example of this when the Nationals candidate Katrina Hodgkinson won the primary vote but was defeated after preferences to Liberal candidate Peta Seaton when Seaton received Labor Party preferences.

Bosnia and Herzegovina

In 2006, the HDZ 1990 broke away from the HDZ BiH this allowed Željko Komšić to gain the Croat membership in the Presidency of Bosnia and Herzegovina with less than 40% which mainly came from Bosniak areas.^{[citation needed]}

Bulgaria

In 2001, the former tsar of Bulgaria Simeon II founded the NDSV. The NDSV won exactly 50% of the seats (120 out of 240 seats) thus barely missing an outright majority. Similarly named parties "Simeon II" Coalition, "National Union for Tsar Simeon II", "National Union Tsar Kiro" Coalition and "National Movement for New Era" (NDNE) got 3.44%, 1.70%, 0.60% and 0.05% respectively.

In Bulgaria, the so-called "blue parties" or "urban right" which include SDS, DSB, Yes, Bulgaria!, DBG, ENP, Coalition For you Bulgaria and Blue Unity frequently get just above or below the electoral threshold depending on formation of electoral alliances: In the EP election 2007, DSB (4.74%) and SDS (4.35%) were campaigning separately and both fell below the natural electoral of around 5 percent. In 2009 Bulgarian parliamentary election, DSB and SDS ran together as Blue Coalition gaining 6.76 percent. In 2013 Bulgarian parliamentary election, campaigning separately DGB received 3.25 percent, DSB 2.93 percent, SDS 1.37 percent and ENP 0.17 percent, thus all of them failed to cross the threshold this even led to a tie between the former opposition and the parties right of the centre. In the EP election 2014, SDS, DSB and DBG ran as Reformist Bloc gaining 6.45 percent and crossing the electoral threshold, while Blue Unity campaigned separately and did not cross the electoral threshold. In 2017 Bulgarian parliamentary election, SDS and DBG ran as Reformist Bloc gaining 3.14 percent, "Yes, Bulgaria!" received 2.96 percent, DSB 2.54 percent, thus all of them failed to cross the electoral threshold. In the EP election 2019, "Yes, Bulgaria!" and DBG ran together as Democratic Bulgaria and crossed the electoral threshold with 6.15 percent. In November 2021, electoral alliance Democratic Bulgaria crossed electoral threshold with 6.37 percent.

Canada

When the cities of Fort William and Port Arthur merged and (in 1969) voted on a name for the new town, the vote was split between the popular choices of "Lakehead" and "The Lakehead", allowing the third option to win, creating the town of Thunder Bay, Ontario.

From 1993 to 2004, the conservative vote in Canada was split between the Progressive Conservatives and the Reform (later the Alliance) Party. That allowed the Liberal Party to win almost all seats in Ontario and to win three successive majority governments.

The 2015 provincial election in Alberta saw the left-wing New Democratic Party win 62% of the seats with 40.6% of the province's popular vote after a division within the right-wing Progressive Conservative Party, which left it with only 27.8% of the vote, and its breakaway movement, the Wildrose Party, with 24.2% of the vote. In 2008, the last election in which the Progressive Conservative Party had been unified, it won 52.72% of the popular vote. The Progressive Conservatives had won every provincial election since the 1971 election, making them the longest-serving provincial government in Canadian history—being in office for 44 years. This was only the fourth change of government in Alberta since Alberta became a province in 1905, and one of the worst defeats a provincial government has suffered in Canada. It also marked the first time in almost 80 years that a left-of-centre political party had formed government in Alberta since the defeat of the United Farmers of Alberta in 1935 and the Depression-era radical monetary reform policies of William Aberhart's Social Credit government. During the 2021 Canadian federal election, it is speculated that the People's Party of Canada might have coast the CPC up to 24 seats.

In Canada, vote splits between the two major left-of-centre parties (Liberals and NDP) assisted the Conservative Party in winning the 2006, 2008, and 2011 federal elections, despite most of the popular vote going to left-wing parties in each race. During the 2022 Ontario General Election, Progressive Conservative Doug Ford won a second term as Premier of the Province of Ontario. The Progressive Conservatives won several ridings due to vote splitting. ONDP and Liberal Party voters combined for 47.8% of votes, whereas Ford emerged victorious with only 40.82% of total votes.

Similarly, in Quebec, it is argued that the success of the Bloc Québécois in elections from 1993 to 2008 was because of the federalist vote being split between the Liberals and the Conservatives.^{[citation needed]}

Czech Republic

In 2021, Přísaha (4.68%), ČSSD (4.65%) and KSČM (3.60%) all failed to cross the 5 percent threshold, thus allowing a coalition of Spolu and PaS. This was also the first time that neither ČSSD nor KSČM had representation in parliament since 1992.

Egypt

In the 2012 Egyptian presidential election, the two candidates who qualified for the runoff election, Freedom and Justice Party candidate Mohamed Morsi (24.8%) and the independent candidate Ahmed Shafik (23.7%), each received more votes than any other candidate, but they failed to get enough votes to prove that each winning candidate was actually more popular than the Dignity Party candidate Hamdeen Sabahi (20.7%), the independent candidate Abdel Moneim Aboul Fotouh (17.5%), or the independent candidate Amr Moussa (11.1%).^{[citation needed]}

France

In France, the 2002 presidential elections have been cited as a case of the spoiler effect: the numerous left-wing candidates, such as Christiane Taubira and Jean-Pierre Chevènement, both from political parties allied to the French Socialist Party, or the three candidates from Trotskyist parties, which altogether totalled around 20%, have been charged with making Lionel Jospin, the Socialist Party candidate, lose the two-round election in the first round to the benefit of Jean-Marie Le Pen, who was separated from Jospin by only 0.68%. Some also cite the case of some districts in which the moderate right and the far right had more than half of the votes together, but the left still won the election; they accuse the left of profiting from the split. Also in the presidential elections 1969 (with five left-wing candidates which combined had 32%), in 2017 (split between four candidates which had 27% combined) and in 2022 (six left-wing candidates with 32% combined), the left failed to reach the run-off which may be traced back the amount of left-of-centre candidates. Similarly in the 1993 parliamentary election, where the green parties ran against the parties of the presidential majority. This led to many right-wing run-offs and the most right-wing dominated parliament since 1968.

In the 2023 French Polynesian legislative election, the anti-separatist A here ia Porinetia did not form an alliance with the Tāpura Huiraʻatira allowing the separatist Tāvini Huiraʻatira to win the run-off with just 44%.

In the 2009 European Parliament election, two right-wing sovereignist lists Libertas France and Debout la République (DLR) competed against each other. Libertas and DLR failed to cross 5% threshold in all but one constituency. Similar vote splitting happened betweeb the two (post-)Trotskyist parties New Anticapitalist Party and Lutte Ouvrière. A similar scenario happened in 2019, when after failed negotiations Debout la France–CNIP (the former previously known as DLR), Popular Republican Union (UPR) and The Patriots ran independetly and gained 3.5%, 1.2% and 0.6% respectively thus falling below the newly introduced national threshold of 5%.

Germany

In the German presidential election of 1925, Communist Ernst Thälmann refused to withdraw his candidacy although it was extremely unlikely that he would have won, and the leadership of the Communist International urged him not to run. In the second (and final) round of balloting, Thälmann shared 1,931,151 votes (6.4%). Centre Party candidate Wilhelm Marx, backed by pro-republican parties, won 13,751,605 (45.3%). The right-wing candidate Paul von Hindenburg won 14,655,641 votes (48.3%). If most of Thälmann's supporters had voted for Marx, Marx likely would have won the election. That election had great significance because after 1930, Hindenburg increasingly favoured authoritarian means of government, and in 1933, he appointed Adolf Hitler as chancellor. Hindenburg's death the following year gave Hitler unchecked control of the German government.

In the 1990 German federal election, the Western Greens did not meet the threshold, which was applied separately for former East and West Germany. The Greens could not take advantage of this, because the "Alliance 90" (which had absorbed the East German Greens) ran separately from "The Greens" in the West. Together, they would have narrowly passed the 5.0 percent threshold (West: 4.8%, East: 6.2%). The Western Greens returned to the Bundestag in 1994.

The post-communist PDS and its successor Die Linke often hovered around the 5 percent threshold: In 1994, it won only 4.4 percent of the party list vote, but won four districts in East Berlin, which saved it, earning 30 MPs in total. In 2002, it achieved only 4.0 percent of the party list vote, and won just two districts, this time excluding the party from proportional representation. This resulted in a narrow red-green majority and a second term for Gerhard Schröder, which would not have been possible had the PDS won a third constituency. In 2021, it won only 4.9 percent of the party list vote, but won the bare minimum of three districts (Berlin-Lichtenberg, Berlin-Treptow-Köpenick, and Leipzig II), salvaging the party, which received 39 MPs.

In the 2013 German federal election, the FDP, in Parliament since 1949, received only 4.8 percent of the list vote, and won no single district, excluding the party altogether. This, along with the failure of the right-wing eurosceptic party AfD (4.7%), gave a left-wing majority in Parliament despite a center-right majority of votes (CDU/CSU itself fell short of an absolute majority by just 5 seats). As a result, Merkel's CDU/CSU formed a grand coalition with the SPD.

Klimaliste has been accused of splitting the vote which would have gone to Alliance 90/The Greens. For example, in the 2021 Baden-Württemberg state election a Red-Green coalition was just a single seat short of a majority while Klimaliste missed the threshold with receiving 0.9% of the vote.

Greece

In Greece, Antonis Samaras was the Minister for Foreign Affairs for the liberal conservative government of New Democracy under Prime Minister Konstantinos Mitsotakis but ended up leaving and founding the national conservative Political Spring in response to the Macedonia naming dispute, resulting in the 1993 Greek legislative election where PASOK won with its leader Andreas Papandreou making a successful political comeback, which was considered to be responsible for the Greek government debt crisis.

Guatemala

In 2019 the different parties to the left of National Unity of Hope (Semilla, Winaq, MLP, URNG, EG, CPO-CRD and Libre) ran with their own lists and presidential candidates. Their highest candidates Thelma Cabrera and Manuel Villacorta archived 10.3% and 5.2% respectively, combined stronger than the main conservative candidate Alejandro Giammattei 13.9% (who was elected in the run-off). If they ran together there wont have been any conservative candidate in the run-off. A similar scenario happened in the 2023 election, in which four right-of-centre candidates (Manuel Conde, Armando Castillo, Edmond Mulet and Zury Ríos) gained just below 11% each, all behind Semilla's candidate Bernardo Arévalo with around 16%.

Hong Kong

In Hong Kong, vote splitting is very common for the pro-democracy camp, which caused it to suffer greatly in many elections, including the 2016 Hong Kong legislative election and the 2015 Hong Kong local elections. Pro-democracy supporters typically have different ideologies and suffer from factional disputes that are exacerbated after the advent of localist camp. However, many have wider aggregate support fewer seats are earned than the pro-Beijing camp, an example being in Kowloon East in which pro-democracy parties got over 55% of cast ballots but won only 2 seats out of 5.^{[citation needed]}

Israel

In April 2019, among the 3 lists representing right-wing to far-right Zionism and supportive of Netanyahu, only one crossed the threshold the right-wing government had increased to 3.25 percent: the Union of the Right-Wing Parties with 3.70 percent, while future Prime Minister Bennett's New Right narrowly failed at 3.22 percent, and Zehut only 2.74 percent, destroying Netanyahu's chances of another majority, and leading to snap elections in September.

Italy

Sicily is traditionally dominated by the centre-right but in the 2012 Sicilian regional election the centre-right was split between Nello Musumeci, Gianfranco Micciché, Mariano Ferro and Cateno De Luca allowing the centre-left Rosario Crocetta to win the election with just 30.5%.^{[citation needed]}

The Italian Left often struggled to meet thresholds after the formation of the Democratic Party, in 2008 most left-wing parties ran on the Rainbow Left list which got 3.08% but other left-wing parties, the Workers' Communist Party (PCL) with 0.57%, the Critical Left with 0.46% and the Communist Alternative Party (PdAC) with 0.01%, still split enough votes for them to fell below the 4% threshold. In 2009 three different left-wing lists competed against each other. The Federation of the Left got 3.39%, Left and Freedom got 3.13% and the PCL got 0.54%, thus all fell short of the 4% threshold. Similarly in 2019, Green Europe got 2.32% and The Left got 1.75%.

New Zealand

In New Zealand, there have been two notable cases of the spoiler effect. In the 1984 general election, the free-market New Zealand Party deliberately ran for office to weaken support former Prime Minister Robert Muldoon, the incumbent. The 1993 general election saw the New Zealand Labour Party's vote split by The Alliance, which has been attributed to the vagaries of the plurality vote. In response to these problems, New Zealand has since adopted mixed-member proportional representation.^{[citation needed]}

While New Zealand First received only 4.07 percent in the 2008 New Zealand general election of the list vote (so it was not returned to parliament), ACT New Zealand won 3.65 percent of the list vote, but its leader won an electorate seat (Epsom), which entitled the party to list seats (4). In the 2011 election, leaders of the National Party and ACT had tea together before the press to promote the implicit alliance (see tea tape scandal). After their victories, the Nationals passed a confidence and supply agreement with ACT to form the Fifth National Government of New Zealand.

Nicaragua

Before the 2006 Nicaraguan presidential election, the Nicaraguan Liberal Alliance broke away from the Constitutionalist Liberal Party. This allowed Daniel Ortega to win the election with 38%, his two liberal opponents got 51% combined.^{[citation needed]}

Norway

In 2009, the Liberal Party received 3.9 percent of the votes, below the 4 percent threshold for leveling seats, although still winning two seats. Hence, while right-wing opposition parties won more votes between them than the parties in the governing coalition, the narrow failure of the Liberal Party to cross the threshold kept the governing coalition in power. It crossed the threshold again at the following election with 5.2 percent.

Paraguay

In the 2008 Paraguayan presidential election, the candidate of the opposition alliance Fernando Lugo won the election with just 42% because Lino Oviedo ran on his own. The two right-wing candidates had 54% together but due to the split of the Colorado Party went into opposition for the first time since 1947.^{[citation needed]}

Poland

In 2015, the United Left achieved 7.55 percent, which is below the 8 percent threshold for multi-party coalitions. Furthermore, KORWiN only reached 4.76 percent, narrowly missing the 5 percent threshold for individual parties. This allowed the victorious PiS to obtain a majority of seats with 37 percent of the vote. This was the first parliament without left-wing parties represented.

Philippines

In the 2004 Philippine presidential election, those who were opposed to Gloria Macapagal Arroyo's presidency had their vote split into the four candidates, thereby allowing Arroyo to win. The opposition had film actor Fernando Poe, Jr. as its candidate, but Panfilo Lacson refused to give way and ran as a candidate of a breakaway faction of the Laban ng Demokratikong Pilipino. Arroyo was later accused of vote-rigging.

Romania

In 2000, the different candidates of the incumbent government got in the Romanian presidential election 11.8% (Stolojan), 9.5% (Isărescu), 6.2% (Frunda) and 3.0% (Roman) respectively. Combined they had more than Corneliu Vadim Tudor of the Greater Romania Party, who got 28.3% in the first round.

Serbia

In Serbia, there are often quite a few nationalist and right-wing parties, which compete independently. Since the rise of Aleksandar Vučić's Serbian Progressive Party, which broke away from the Serbian Radical Party in 2008, vote splitting became common among them. The most extreme cases of vote splitting were in 2014, none of the nationalist lists (DSS, SRS, Dveri, Third Serbia, "Patriotic Front" and the Russian Party, a nominally Russian minority party) made it above 4.2% thus neither of them won seats despite having a total of 10.6%. and in 2020, the POKS (2.7%), DJB (2.3%), the DSS (2.2%) and the SRS (2.1%) alongside smaller parties all ended up below the 3% threshold, which was introduced to make it easier for parties after the main opposition alliance called for a boycott. Only the Serbian Patriotic Alliance gained 3.8% in their first and only election.

Slovakia

2002. The True Slovak National Party (PSNS) split from Slovak National Party (SNS), and Movement for Democracy (HZD) split from the previously dominant People's Party – Movement for a Democratic Slovakia. All of them failed to cross the 5 percent threshold with PSNS having 3.65 percent, SNS 3.33 percent and HZD 3.26 percent respectively, thus allowing a center-right coalition despite having less than 43 percent of the vote.

In 2016, the Christian Democratic Movement achieved 4.94 percent missing only 0.06 percent votes to reach the threshold after #SIEŤ split from KDH which meant the first absence of the party since the Velvet Revolution and the first democratic elections in 1990.

In 2020, Velvet Revolution in which no party of the Hungarian minority crossed the 5 percent threshold. The vote was split between Hungarian Community Togetherness with 3.9% and Most–Híd with 2.1%.

Before the 2024, Republic broke away from the People's Party Our Slovakia (ĽSNS). Republic received 4.75% and the ĽSNS 0.84%.

South Korea

In 1987, Roh Tae-woo won the South Korean presidential election with just under 36% of the popular vote because his two main liberal rivals split the vote. A similar scenario happened when in 1997 won by just Kim Dae-jung 40.3% because his two main conservative rivals split the vote.

Taiwan

In the 2000 presidential election in Taiwan, James Soong left Kuomintang (KMT) party and ran as an independent against KMT's candidate Lien Chan. This caused vote-splitting among KMT voters and resulted in victory for Democratic Progressive Party's candidate, Chen Shui-bian. It is the first time in Taiwan history that the KMT did not win a presidential election, and it became the opposition party.

A similar scenario happened in 2024, when after the opposition candidates Hou Yu-ih (KMT) and Ko Wen-je (Taiwan People's Party) failed to reached an agreement, Lai Ching-te (DPP) won with just 40 % of the vote.

Turkey

Regular military coups in the second half of the 20th century led to a situation, where two similar centre-left kemalist parties, the Republican People's Party (CHP) and the Democratic Left Party (DSP), and centre-right kemalist parties, the True Path Party (DYP) and Motherland Party (ANAP), competed against another. In the 2002 general election, the centre-left (CHP, DSP, NTP) got 21.76% and the centre-right (DYP, ANAP, YP, LDP) got 15.89% but because of the split only the CHP and the new Justice and Development Party (AKP) made it above the 10% threshold with the AKP having 66% of the seats with just 34.28% of the vote. Attempts to merge ANAP and DYP before the 2007 election failed and the Democrat Party (the successor of DYP) only won 5.4%.

United Kingdom

In the 1994 European Elections, Richard Huggett stood as a "Literal Democrat" candidate for the Devon and East Plymouth seat, with the name playing on that of the much larger Liberal Democrats. Huggett took over 10,000 votes, and the Liberal Democrats lost by 700 votes to the Conservative Party. The Registration of Political Parties Act 1998, brought in after the election, introduced a register of political parties and ended the practice of deliberately confusing party descriptions.

In the run up to 2019 UK General Election, the Brexit Party, led by former UKIP leader Nigel Farage, initially put up candidates in 600 seats after a strong showing for the newly formed party in the 2019 European Elections, but days later, he reversed his position after Conservative British Prime Minister Boris Johnson stated that he would not consider an electoral pact with the Brexit Party. That was seen as benefiting the Conservative Party and disadvantaging the Labour Party. Farage later encouraged voters not to vote for the Labour Party in areas that traditionally favoured it but voted to leave in the 2016 EU Membership Referendum but instead to vote tactically. After the Conservatives' decisive victory, it was suggested by some media outlets and political analysts that Farage had acted as "kingmaker" and stalking horse and effectively won the election for the Tories, as Farage's decision avoided splitting the vote.

United States

Since 1990, the Republican Party's presidential ticket, according to the research cited below, has benefited most from the spoiler effect of the plurality voting system that chooses electors for the electoral college. The year 2000 was an especially clear case when Al Gore would likely have won without vote splitting by one or more of the third-party tickets on the ballot. Which party benefits from a third-party ticket depends on the election and the candidates.

President (since 1990)

• For the 2016 United States presidential election and 2020 United States presidential election, some analyses have found the impact of third party candidates only on the margin of victory. Some attribute Biden’s election in 2020 to the lack of vote splitting, with studies of 2016 third-party voters showing them much more likely to vote for Biden in 2020.
• In 2000, Al Gore, the Democratic candidate, lost to George W. Bush due to a difference of 537 votes in the state of Florida. Green Party candidate and progressive Ralph Nader received 97,421 votes in Florida on a platform most similar to Gore's. Exit polling and surveys have estimated that around 47% of Nader supporters said they would have voted for Gore if Nader didn't run (21% Bush and 32% neither). Vote splitting has also been called the "Nader Effect" as a result.
• Analysis of surveys and exit poll data from the 1992 presidential election predicts Bill Clinton winning regardless of Ross Perot's campaign but disagreements remain on which candidate lost more votes to Perot.

President (before 1970)

• In 1968, George Wallace ran for president as the American Independent Party's nominee and was the most recent third-party candidate to win a state.
• In 1912, Progressive Party candidate Theodore Roosevelt won almost 700,000 votes more than did the Republican incumbent, William Howard Taft. Republicans, who, after Woodrow Wilson won the 1912 election, became concerned that Roosevelt might return to split the Republican vote again.
• In the 1884 presidential election, the Prohibition Party's presidential nominee, former Republican Governor John St. John, took 147,482 votes, with 25,006 votes coming from New York, where Grover Cleveland defeated James G. Blaine by just 1,149 votes, allowing Cleveland to defeat Blaine in a very close contest (219-182 in the electoral college and a margin of 0.57% in the popular vote). Republicans were so angered by St. John's party switch, which caused their first presidential election defeat since 1856, that on November 27, 1884, an effigy of St. John was burned in Topeka, Kansas in front of a crowd of three thousand people.

Other races

• In the 1934 Oregon gubernatorial election, Republican Peter Zimmerman ran as an independent, receiving 31.7% of the vote compared to Democratic victor Charles Martin's 38.6% and Republican nominee Joe Dunne's 28.7%. Altogether, the Republicans received 60.4% of the vote.^{[citation needed]}
• In the special 2003 California gubernatorial race won by Republican Arnold Schwarzenegger, which did not involve a primary election and which listed 135 candidates on the ballot, concerns about vote splitting caused the Democrats to withdraw all but one of their major candidates and the Republicans to withdraw most of their candidates. Likewise, many supporters of Republican Tom McClintock changed their mind at the last minute and voted for Schwarzenegger for fear of the Democratic candidate, Cruz Bustamante, winning.^{[citation needed]}
• An analysis of 2006 to 2012 general election races in the U.S. found 1.5% were spoiled by third-party candidates, according to Philip Bump.
• In 2008, Democrat Al Franken was elected the junior senator from Minnesota, defeating Norm Coleman by only 0.1%. Independent candidate Dean Barkley received over 15% of the vote, and a 2014 analysis by Time found that without Barkley in the race, Franken would have lost the election to Coleman.
• As a result of the 2011 Wisconsin protests and subsequent recall elections, the Wisconsin Republican Party has encouraged spoiler candidates to run in the recall elections on the Democrat ticket in order to force the Democrats into a primary election. Republicans argued that this would even the playing field in the recalls, as incumbents facing recall did not have the time to campaign due to their work load in the state senate.
• In Maine's 2010 and 2014 gubernatorial elections, Eliot Cutler ran as a left-wing independent. In the 2010 election Paul LePage narrowly defeated him with 218,065 votes to 208,270 votes with the Democratic nominee Libby Mitchell receiving 109,387 votes and possibly spoiling the election for Cutler. However, in 2014 Cutler performed worse and only received 51,518 votes, but it was still greater than the difference between LePage and Mike Michaud causing a possible spoiler effect. These elections lead to an increase support in ranked choice voting leading to Maine adopting the voting system due to LePage's unpopularity and him winning twice only with pluralities.
• In both the 2013 Virginia gubernatorial election and the 2014 Virginia US Senate Election, Libertarian Robert Sarvis received a number of votes greater than the difference between the Republican and Democratic candidates.
• Several races in the 2014 election cycle were allegedly influenced by spoiler candidates, most notably Hawaii's gubernatorial elections and the Kansas senatorial race. In the Mississippi senatorial Republican primary, a paper candidate, Thomas Carey, who received less than two percent of the vote prevented both top contenders, incumbent Thad Cochran and challenger Chris McDaniel, from avoiding a runoff. Had Carey not run, the race between McDaniel and Cochran would have avoided a runoff.^{[citation needed]}

• Electoral threshold
• Independence of clones
• Independence of irrelevant alternatives
• Instant-runoff voting
• Strategic nomination
• Tactical voting