Instant runoff voting is a method of electing one political candidate to office from a list of more than two, but it can also be used for other group decisions. Voters rank the candidates from favorite to least favorite, with only their top choices being counted each time. Ballots are counted, and a series of simulated rounds is conducted. If no candidate has a majority of the votes in any round, the candidate with the fewest votes is eliminated, and those voters' next choice votes are then counted. This is repeated until a candidate has a majority.
Instant runoff voting has been used in Australia's lower house for more than 80 years. That house is strongly dominated by two parties. It has also been used to elect mayors in some cities in the United States. Voter turn out is typically the same as with plurality voting.
Proponents believe instant runoff voting allows them to vote for their first choice candidate and still help the lessor of evils if the first choice is eliminated. They believe Instant Runoff Voting to be the only way let voters vote their true intentions and undermine the two-party system. By having more candidates on the ballot, incumbents are more likely to be kicked out of office.
Opponents argue that if at least three candidates have a chance of winning, voting for one's favorite could cause a compromise candidate to lose in the first round. Their favorite might then lose against the least preferred candidate in the second round. Voters' votes cannot be transferred to their second choice if their second choice is eliminated before their first choice is. Voters often use their first choice vote for a compromise vote, the same as with plurality.
While theoretically simple, instant runoff voting often requires computers because the rankings on each ballot matter for determining the elimination order and can not be counted in aggregate. Opponents of Instant runoff voting often oppose computer counting of ballots, since it is difficult for ordinary citizens to count the ballots by hand and catch any fraud. The fact that a candidate has fewer votes does not mean the candidate is less popular but that the candidate was squeezed out on both sides of the political spectrum. Instant runoff voting can eliminate centrists in the last elimination.