I was surprised to hear that run-off elections were to take place in Georgia.

Presumably this is part of a system of "proportional representation", whereby in circumstances where there are more than two candidates, a winner with more than 50% support has to be discovered.

There are various voting systems, used around the world, particularly in Europe to achieve this - multi-member constituencies, run-offs, single transferable votes etc. In Britain none are used - the "first-past-the-post" system is used universally in parliamentary and local government elections.

Does the fact that "run-offs" are being used in Georgia, mean that they are governed by the rules of the US Senate, or is this a rule peculiar to Georgia?

  • 4
    "In Britain none are used" - not really true; e.g. elections to the Welsh Senedd, Scottish Parliament. Even within England, the London Assembly also uses a form of PR.
    – CDJB
    Nov 9, 2020 at 9:30
  • @CDJB Thank you for pointing that out. I had quite forgotten the devolved assemblies - shame on me. I was thinking it only applied in EU elections, which of course no longer exist - more's the pity.
    – WS2
    Nov 9, 2020 at 11:33
  • 2
    Georgia's run-off senate elections are not proportional at all. For proportional representation you need to have some kind of multi-member districts. This time there are two elections in Georgia because a senator resigned, but the two elections are independent. It is possible, perhaps even likely, that one party will win both elections on Jan 5. If it was proportional the Republican and Democratic parties would most likely each win one senator. (One party's votes would need to be above ~66% to win both seats in a proportional election, depending on the exact election method.) Nov 10, 2020 at 7:32
  • 1
    I think you're confusing proportional representation (each party gets seats in proportion to its share of the vote within a region) with preferential/runoff voting (if your first choice doesn't get in, you get some influence in the contest between the other candidates). Although they sometimes occur together, they're not the same concept. Nov 10, 2020 at 19:59
  • @curiousdannii You can have proportional representation in a system with single member districts by having bonus seats to reconcile the single member district results to the overall outcome in terms of party support, or by having unequal voting power as corporations do in proxy voting electons.
    – ohwilleke
    Nov 10, 2020 at 20:46

3 Answers 3


It is not related to proportional representation. Most states for every election use first-past-the-post (FPTP).

The Senate has no rules for how Senators are elected, except that it is done by popular vote. They were originally appointed by state legislatures. Senators, unlike Representatives, can be appointed when a vacancy arises (rules depend on state). But an election must be held eventually. In fact, that's why there are two (independent!) Senate elections in Georgia this year, because Senator Johnny Isakson resigned in 2019, and appointee Kelly Loeffler must now earn her seat.

In the specific case of Georgia, there will be two run-offs because no candidate reached a majority in either general election. A similar system is Louisiana (and according to that page, Mississippi and Texas special elections). In these elections, the run-off is held if and only if there is no majority in the first round, after the general election.

Finally, Washington and California use a "jungle primary" where the top two candidates of any party advance to the general. This system is different in that even if a candidate gets a majority in the primary, they still face off against #2 in the general. Additionally, these primaries occur before the general, around late summer.

Here is a nice map, from Wikipedia. FPTP in red, with the states discussed above highlighted. Maine (pink) uses instant-run off voting (IRV), but Susan Collins got a majority in 2020.

Election types in the US

  • Louisiana also has a jungle primary, although it isn't called that there. Washington and California copied Louisiana which in turn copied France.
    – ohwilleke
    Nov 10, 2020 at 20:43
  • 1
    LA/GA are different from CA/WA in two ways; 1) Timing: WA and CA have their jungle primaries before election day and the runoffs on election day, while LA and GA have their "primaries" on election day and runoffs after. 2) What happens if a candidate gets a majority: In WA and CA, the top two candidates go to runoff even if one gets a majority. In LA and GA, if a candidate gets a majority on election day, no runoff is held. (For completeness, GA also has normal party primaries before election day, but not for special elections; LA only has party primaries for presidential candidates.)
    – A. R.
    Jan 7, 2021 at 17:28
  • For presidential elections, most states have party primaries and an FPTP winner-take-all election on election day. Only Maine and Nebraska differ here, both states assigning two electors to the statewide winner and one to the winner in each US house district. Nebraska uses FPTP and Maine uses IRV.
    – A. R.
    Jan 7, 2021 at 17:33
  • @AndrewRay Thanks. I included your clarifications from your first comment; but I'll leave the presidential notes for a question about presidential elections :) Jan 7, 2021 at 17:45

I would see run-offs as as a wrinkle on majority/plurality vote, not as anything like proportional representation.

  • PR tries to create a legislature whose composition represents the public vote, possibly with rounding and cutoff effects.
  • Majority/plurality tries to select one representative, either the plurality candidate in the first-and-only round or a majority candidate in one-or-several rounds.
  • 1
    It's a worse version of preferential Instant Runoff Voting. There's really no reason to have separate elections when they could just specify preferences in the first place! Nov 10, 2020 at 7:20
  • Thanks for that, +1. But what is the extent of this "wrinkle". Is the a Georgia rule, or is it US-wide for the Senate?
    – WS2
    Nov 10, 2020 at 8:37
  • 4
    @WS2, the rules differ from state to state.
    – o.m.
    Nov 10, 2020 at 15:14

Georgia, like Louisiana, California, France, and the City and County of Denver in single member candidate races and many other jurisdictions, has what is called a "two round system" in which a candidate wins a first round of an election only by getting a majority of the vote cast, and if no candidate gets a majority, a second round election is held between the top two finishers. Most U.S. jurisdictions, however, have "single member district plurality" voting systems, also called "first past the post" voting systems, in which the candidate with the most votes wins, even if that candidate doesn't receive a majority of the votes cast.

The purpose of a system like this is not precisely proportional representation. What it does is to eliminate "spoiler effect" caused when two or more candidates with similar views are both competing in a race with three or more candidates and split the vote, even though the similar candidates would be the second choice of the other.

It is "instant runoff voting" but without the instant part.

There are some good reasons by a two round system is more common than instant runoff voting.

  1. It is easier to administer. Elections officials need to extract only one choice from each ballot in any given election.

  2. Lots of average people have trouble thinking hypothetically. They know who they prefer, but imagining a reality where their favored candidate doesn't perform well and they have to choose another candidate is harder.

  3. It takes a voter more effort and research to decide on both a first and second (and possibly third or more distant) choice than just deciding on a favorite choice. In two round system, this research is only needed when there is a runoff and your favorite candidate doesn't make it to the runoff, and once that does happen, your research is limited to just two candidates, rather than a large field of candidates and is more salient and hence voters are more motivated to do it.

  • In "instant runoff voting" a virtual runoff election is held based upon the expressed second and if necessary third place choices of voters at the initial election if no candidate receives a majority of first place votes. In a two step system, if no candidate receives a majority, a runoff election is held a month or two later instead of "instantly."
    – ohwilleke
    Nov 10, 2020 at 22:01
  • 1
    @AzorAhai-him- Fixed.
    – ohwilleke
    Nov 10, 2020 at 22:22
  • Against those advantages of a run-off versus "the single transferable vote" system, is the signal disadvantage that it is much more expensive. You have to stage a whole new ballot on a later day.
    – WS2
    Nov 10, 2020 at 23:48
  • 1
    I assume you are speaking from an American vantage point here. The US has the quintessential two-party system. That used to be the case in Britain, but we have in recent decades had a strong third party - the Liberal Democrats - and nationalist parties in Wales and Scotland - to say nothing of the Greens. But while other EU countries address this through PR - Britain still, by and large has a FPTP system. The single-transferable vote, with a second-choice on ballot papers would require little voter education. What has happened is that people have adopted tactical voting (continued)
    – WS2
    Nov 11, 2020 at 7:54
  • 1
    There are cases where the result of a two-round system are not the same as an IRV system, particularly where there mare more than three candidates for a single seat. Also, the chance for a 2nd round of campaigning when only 2 options are left changes things. One might debate which is better. Also, the 2-round system is significantly older than IRV or STV. Jan 7, 2021 at 22:30

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