If a candidate collects more than 50 percent of the vote, that person is the winner. If not, the last-place candidate is eliminated, and the second-choice votes for that candidate would be redistributed among the remaining candidates. The process continues until one candidate has a majority of votes.

If approved, the new system would be in effect in time for the 2021 mayoral election — an electoral tsunami that is expected to attract more than 500 candidates, as 35 of the City Council’s 51 seats, two citywide offices (mayor and comptroller) and all five borough presidencies will be vacant because of term limits.

One of the main benefits of ranked-choice voting, proponents say, is that it reduces the chance of a fringe candidate winning an election; under that scenario, mainstream candidates split the majority of the vote, leaving just enough votes for a long shot to win.

Ranked choice also tends to discourage negative campaigning because candidates may not want to alienate supporters of rival candidates; it also encourages candidates to go beyond their base of supporters.

“What we see in the current system is that politicians are advised to dig down into their base of existing supporters and don’t worry about voters in other communities who didn’t vote for you last time,” said Susan Lerner, executive director of Common Cause New York, a good-government group.