Two-round system

The two-round system (TRS or 2RS), also called ballotage, top-two runoff, or two-round plurality (as originally termed in French^[1]), is a voting method used to elect a single winner. In the United States, it is often called a jungle or nonpartisan primary. The system is sometimes also called plurality-with-runoff,^[2]^[2] although this term can also be used to refer to other in the plurality-runoff family of methods. The two-round system first emerged in France, and has since become the most common single-winner electoral system worldwide.^[3]^[1]

In a two-round system, both rounds are held using choose-one voting, where the voter marks their favorite candidate. The two candidates with the most votes in the first round proceed to a second round, where all other candidates are excluded.^{[note 1]} The two-round system is widely used in the election of legislative bodies and directly elected presidents. It is closely related to other members of the plurality-runoff family of methods (including plurality voting, ranked-choice voting, and plurality-with-primaries).

In the United States, the system is used to elect most public officials from Mississippi, Georgia, Louisiana, California, and Washington. While not generally considered as a two-round system, the combination of a two-party system with partisan primaries used in the rest of the country is very similar in terms of both structure and results,^[4]^[5] leading political scientists to describe it as behaving like an "unusual two-round system" in practice.^[6]^[7]

^ ^a ^b Sabsay, Daniel Alberto (1995). "El sistema de doble vuelta o ballotage" (PDF). Lecciones y Ensayos (62). Facultad de Derecho de la Universidad de Buenos Aires. ISSN 0024-0079. Archived (PDF) from the original on 2022-11-07. Retrieved 2024-07-18.
^ ^a ^b Martinelli, César (2002-10-01). "Simple plurality versus plurality runoff with privately informed voters". Social Choice and Welfare. 19 (4): 901–919. doi:10.1007/s003550200167. ISSN 1432-217X.
^ "El ballotage, con raíces históricas en Francia". El Día. 1 November 2015. Archived from the original on 2023-10-23. Retrieved 2024-07-18.
^ Hill, Seth J.; Kousser, Thad (2015-10-17). "Turning Out Unlikely Voters? A Field Experiment in the Top-Two Primary". Political Behavior. 38 (2): 413–432. doi:10.1007/s11109-015-9319-3. ISSN 0190-9320. S2CID 54541384. Two groups that were predicted by advocates to increase their participation in response to this reform—those registered with third parties or no-party-preference registrants (independents) who were not guaranteed a vote in any party's primary before the move to the top-two—also show declines in turnout
^ Kousser, Thad. "California's jungle primary sets up polarized governor's race for November". The Conversation. Retrieved 2018-06-23. The idea was that by opening up primaries to all voters, regardless of party, a flood of new centrist voters would arrive. That would give moderate candidates a route to victory .. Candidates did not represent voters any better after the reforms, taking positions just as polarized as they did before the top two. We detected no shift toward the ideological middle.
^ Santucci, Jack; Shugart, Matthew; Latner, Michael S. (2023-10-16). "Toward a Different Kind of Party Government". Protect Democracy. Archived from the original on 2024-07-16. Retrieved 2024-07-16. 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) 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).
^ Gallagher, Michael; Mitchell, Paul (2005-09-15). "The American Electoral System". The Politics of Electoral Systems. OUP Oxford. p. 192. ISBN 978-0-19-153151-4. American elections become a two-round run-off system with a delay of several months between the rounds.

Cite error: There are <ref group=note> tags on this page, but the references will not show without a {{reflist|group=note}} template (see the help page).

[SAB23-1] Sabsay, Daniel Alberto (1995). "El sistema de doble vuelta o ballotage" (PDF). Lecciones y Ensayos (62). Facultad de Derecho de la Universidad de Buenos Aires. ISSN 0024-0079. Archived (PDF) from the original on 2022-11-07. Retrieved 2024-07-18.

[:13-2] Martinelli, César (2002-10-01). "Simple plurality versus plurality runoff with privately informed voters". Social Choice and Welfare. 19 (4): 901–919. doi:10.1007/s003550200167. ISSN 1432-217X.

[ED-RAÍCES23-3] "El ballotage, con raíces históricas en Francia". El Día. 1 November 2015. Archived from the original on 2023-10-23. Retrieved 2024-07-18.

[5] Hill, Seth J.; Kousser, Thad (2015-10-17). "Turning Out Unlikely Voters? A Field Experiment in the Top-Two Primary". Political Behavior. 38 (2): 413–432. doi:10.1007/s11109-015-9319-3. ISSN 0190-9320. S2CID 54541384. Two groups that were predicted by advocates to increase their participation in response to this reform—those registered with third parties or no-party-preference registrants (independents) who were not guaranteed a vote in any party's primary before the move to the top-two—also show declines in turnout

[:23-6] Kousser, Thad. "California's jungle primary sets up polarized governor's race for November". The Conversation. Retrieved 2018-06-23. The idea was that by opening up primaries to all voters, regardless of party, a flood of new centrist voters would arrive. That would give moderate candidates a route to victory .. Candidates did not represent voters any better after the reforms, taking positions just as polarized as they did before the top two. We detected no shift toward the ideological middle.

[:03-7] Santucci, Jack; Shugart, Matthew; Latner, Michael S. (2023-10-16). "Toward a Different Kind of Party Government". Protect Democracy. Archived from the original on 2024-07-16. Retrieved 2024-07-16. 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) 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).

[8] Gallagher, Michael; Mitchell, Paul (2005-09-15). "The American Electoral System". The Politics of Electoral Systems. OUP Oxford. p. 192. ISBN 978-0-19-153151-4. American elections become a two-round run-off system with a delay of several months between the rounds.

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