Editing Two-round system (section)

{{short description|Voting system}}
{{for|other types of runoff-voting systems|Runoff voting (disambiguation)}}
{{More sources|date=July 2024}}
{{electoral systems|expanded=Single-winner methods}}
[[File:Electoral systems for heads of state map direct.svg|thumb|333x333px|Countries by electoral system used to (directly) elect their head of state:{{legend|#ff0000|[[First-past-the-post]]}}{{legend|#a02c5a|Two-round system}}{{legend|#ff80e5|[[Instant-runoff voting]]}}]][[File:TRS_ballot_papers.svg|thumb|332x332px|Runoff voting ballots]]The '''two-round system''' ('''TRS''' or '''2RS'''), sometimes called '''ballotage''', '''top-two runoff''', or '''two-round [[First-past-the-post voting|plurality]]''',<ref name="SAB2322">{{cite journal |last=Sabsay |first=Daniel Alberto |date=1995 |title=El sistema de doble vuelta o ballotage |url=http://www.derecho.uba.ar/publicaciones/lye/revistas/62/el-sistema-de-doble-vuelta-o-ballotage.pdf |url-status=live |publisher=Facultad de Derecho de la Universidad de Buenos Aires |issn=0024-0079 |archive-url=https://web.archive.org/web/20221107171722/http://www.derecho.uba.ar/publicaciones/lye/revistas/62/el-sistema-de-doble-vuelta-o-ballotage.pdf |archive-date=2022-11-07 |access-date=2024-07-18 |number=62 |periodical=Lecciones y Ensayos}}<!-- auto-translated from Spanish by Module:CS1 translator --></ref> is a single-winner [[electoral system]] which aims to elect a member who has support of the majority of voters. The two-round system involves one or two rounds of [[First-past-the-post voting|choose-one voting]], where the voter marks a single favorite candidate in each round. If no one has a majority of votes in the first round, the two candidates with the most votes in the first round move on to a second election (a second round of voting).{{NoteTag|Some jurisdictions allow for runoffs with multiple candidates if two candidates tie for second, or if several candidates receive enough votes. The vast majority of jurisdictions do not hold a runoff if some candidate wins a majority of the first-round vote (as the candidate with a majority will win even if all voters against them in the 1st round support their opponent in the 2nd round).}} The two-round system is in the family of [[plurality voting]] systems that also includes [[first-preference plurality|single-round plurality]] (FPP). Like [[Instant-runoff voting|instant-runoff (ranked-choice) voting]] and first past the post, it elects one winner.<ref name=":02">{{Cite book |last1=Aubin |first1=Jean-Baptiste |url=https://hal.science/hal-04631154/ |title=A simulation-based study of proximity between voting rules |last2=Gannaz |first2=Irène |last3=Leoni-Aubin |first3=Samuela |last4=Rolland |first4=Antoine |date=July 2024}}</ref><ref name=":1322">{{Cite journal |last=Martinelli |first=César |date=2002-10-01 |title=Simple plurality versus plurality runoff with privately informed voters |url=https://doi.org/10.1007/s003550200167 |journal=Social Choice and Welfare |language=en |volume=19 |issue=4 |pages=901–919 |doi=10.1007/s003550200167 |issn=1432-217X}}</ref> 

The two-round system first emerged in [[France]] and has since become the most common single-winner [[electoral system]] worldwide.<ref name="SAB2322" /><ref name="ED-RAÍCES2322">{{cite web |date=1 November 2015 |title=El ballotage, con raíces históricas en Francia |url=https://www.eldia.com/nota/2015-11-1-el-ballotage-con-raices-historicas-en-francia |url-status=live |archive-url=https://web.archive.org/web/20231023020955/https://www.eldia.com/nota/2015-11-1-el-ballotage-con-raices-historicas-en-francia |archive-date=2023-10-23 |access-date=2024-07-18 |website=El Día}}<!-- auto-translated from Spanish by Module:CS1 translator --></ref> Despite this, runoff-based rules like the two-round system and RCV have faced criticism from [[Social choice theory|social choice theorists]] as a result of their susceptibility to [[center squeeze]] (a kind of [[spoiler effect]] favoring extremists) and the [[no-show paradox]].<ref name="Merrill 198422">{{Cite journal |last=Merrill |first=Samuel |date=1984 |title=A Comparison of Efficiency of Multicandidate Electoral Systems |url=http://dx.doi.org/10.2307/2110786 |journal=American Journal of Political Science |volume=28 |issue=1 |pages=23–48 |doi=10.2307/2110786 |issn=0092-5853 |jstor=2110786 |quote=However, squeezed by surrounding opponents, a centrist candidate may receive few first-place votes and be eliminated under Hare. |via=|url-access=subscription }}</ref><ref name="Merril 19852222">{{Cite journal |last=Merrill |first=Samuel |date=1985 |title=A statistical model for Condorcet efficiency based on simulation under spatial model assumptions |url=http://dx.doi.org/10.1007/bf00127534 |journal=Public Choice |volume=47 |issue=2 |pages=389–403 |doi=10.1007/bf00127534 |issn=0048-5829 |quote=the 'squeeze effect' that tends to reduce Condorcet efficiency if the relative dispersion (RD) of candidates is low. This effect is particularly strong for the plurality, runoff, and Hare systems, for which the garnering of first-place votes in a large field is essential to winning |via=|url-access=subscription }}</ref><ref name=":4">{{cite journal |last1=Keskin |first1=Umut |last2=Sanver |first2=M. Remzi |last3=Tosunlu |first3=H. Berkay |date=August 2022 |title=Monotonicity violations under plurality with a runoff: the case of French presidential elections |url=https://hal.science/hal-03413280/document |journal=Social Choice and Welfare |volume=59 |issue=2 |pages=305–333 |doi=10.1007/s00355-022-01397-4}}</ref> This has led to the rise of [[electoral reform]] movements which seek to replace the two-round system with other systems like [[rated voting]], particularly in France.<ref name=":4" /><ref>{{Cite journal |last=Balinski |first=Michel |last2=Laraki |first2=Rida |date=2020-03-01 |title=Majority judgment vs. majority rule |url=https://link.springer.com/article/10.1007/s00355-019-01200-x |journal=Social Choice and Welfare |language=en |volume=54 |issue=2 |pages=429–461 |doi=10.1007/s00355-019-01200-x |issn=1432-217X}}</ref> 

As well, TRS means voters sometimes have to gather to vote a second time, and sometimes the intervening period of time is rife with discord.<ref>Advantages and disadvantages of Two-Round System https://aceproject.org/ace-en/topics/es/esd/esd01/esd01e/esd01e01/mobile_browsing/onePag accessed April 25, 2025 </ref>

In the United States, the first round is often called a '''jungle''' or '''top-two primary'''. [[Georgia (U.S. state)|Georgia]], [[Louisiana]], [[California]], and [[Washington (state)|Washington]]{{NoteTag|California and Washington describe the first round as a [[nonpartisan primary]] and hold the second round as part of their [[general election]]s (regardless of whether candidates receive 50% of the first-round vote).}} use the two-round system for all non-presidential elections. [[Mississippi]] uses it for state offices.<ref>{{Cite web |title=Electoral systems in Mississippi |url=https://ballotpedia.org/Electoral_systems_in_Mississippi |access-date=2025-02-12 |website=Ballotpedia |language=en}}</ref> Most other states use a [[partisan primary]] system that is often described as behaving like a two-round system in practice, with primaries narrowing down the field to two frontrunners.<ref name=":0322">{{Cite web |last1=Santucci |first1=Jack |last2=Shugart |first2=Matthew |last3=Latner |first3=Michael S. |date=2023-10-16 |title=Toward a Different Kind of Party Government |url=https://protectdemocracy.org/work/toward-a-different-kind-of-party-government/ |url-status=live |archive-url=https://web.archive.org/web/20240716205506/https://protectdemocracy.org/work/toward-a-different-kind-of-party-government/ |archive-date=2024-07-16 |access-date=2024-07-16 |website=Protect Democracy |language=en-US |quote="Finally, we should not discount the role of primaries. When we look at the range of countries with [[first-past-the-post]] (FPTP) elections (given no primaries), none with an assembly larger than Jamaica’s (63) has a strict two-party system. These countries include the [[United Kingdom]] and [[Canada]] (where multiparty competition is in fact nationwide). Whether the U.S. should be called ‘FPTP’ itself is dubious, and not only because some states (e.g. [[Georgia (US State)|Georgia]]) hold runoffs or use the [[alternative vote]] (e.g. [[Maine]]). '''Rather, the U.S. has an unusual two-round system in which the first round winnows the field. This usually is at the intraparty level, although sometimes it is without regard to party (e.g. in Alaska and California).'''"}}</ref><ref>{{Cite book |last1=Gallagher |first1=Michael |title=The Politics of Electoral Systems |last2=Mitchell |first2=Paul |date=2005-09-15 |publisher=OUP Oxford |isbn=978-0-19-153151-4 |page=192 |language=en |chapter=The American Electoral System |quote="American elections become a two-round run-off system with a delay of several months between the rounds." |chapter-url=https://books.google.com/books?id=Igdj1P4vBwMC&q=%22American+elections+become+a+two-round+run-off+system+with+a+delay+of+several+months+between+the+rounds.%22&pg=PA3}}</ref><ref>{{Citation |last1=Bowler |first1=Shaun |title=The United States: A Case of Duvergerian Equilibrium |date=2009 |work=Duverger's Law of Plurality Voting: The Logic of Party Competition in Canada, India, the United Kingdom and the United States |pages=135–146 |url=https://link.springer.com/chapter/10.1007/978-0-387-09720-6_9 |access-date=2024-08-31 |place=New York, NY |publisher=Springer |language=en |doi=10.1007/978-0-387-09720-6_9 |isbn=978-0-387-09720-6 |quote=In effect, the primary system means that the USA has a two-round runoff system of elections. |last2=Grofman |first2=Bernard |last3=Blais |first3=André|url-access=subscription }}</ref>  ([[Alaska]] and [[Maine]] use the [[Instant-runoff voting]] system, the ranked-choice voting (RCV) system, which unlike TRS does not require multiple rounds of voting.)