When the Bottom Candidate Drops, Their Votes Move Up

On a ranked-choice ballot, you write a 1 next to your favorite, a 2 next to your backup, and so on as far as you care to go. The count starts by tallying everyone's first choice. If anyone has more than half the vote, the election is over. Most of the time, no one does.

When no candidate clears the bar, the lowest-placed candidate is eliminated and their ballots are reassigned to whoever those voters ranked second. The count repeats. Eliminate, redistribute, retally — until one candidate sits above 50 percent. The procedure dates back to a Massachusetts Institute of Technology professor named William Robert Ware, who proposed it in the 1870s.

Ireland has elected its president this way since 1937. Australia has used it for federal House elections since 1918. The United States uses it in the state of Maine, in New York City municipal elections, and a growing list of other cities and states. Maine adopted it by referendum in 2016 after a string of three-way races where governors won with under 40 percent of the vote.

The most-cited benefit is that the method dampens the spoiler effect: a niche candidate no longer mathematically guarantees the victory of the major-party candidate that niche voters like least. The most-cited cost is that ballots take longer to count, sometimes much longer. New York's 2021 mayoral primary needed two weeks. Critics also note that the system can still produce winners who would lose a head-to-head matchup against another candidate, a quirk known as a Condorcet failure.