Ranked choice voting makes its debut in New York City's mayoral primary Tuesday in one of the most high-profile tests yet for a system  gaining use in pockets across the U.S.

The system is based on a simple premise: Democracy works better if people aren't forced to make an all-or-nothing choice with their vote. Rather than pick just one candidate, voters get to rank several in order of preference. Even if a voter's top choice doesn't have enough support to win, their rankings of other candidates still play a role in determining the victor. But the system is more complex than a traditional election, making it tough to forecast a winner. It could take longer to get results. But the system is tough to grasp. It requires voters to do a lot more research. It also makes races less predictable. Transparency and trust are also potential problems. 

In New York City's version, voters get to rank up to five candidates, from first to last, on their ballot. If one candidate is the first choice of a majority of voters - more than 50% - that person wins the race outright, just like in a traditional election. If nobody hits that threshold, ranked choice analysis kicks in. Vote tabulation is done in rounds, and all rounds of counting are done by computer in a process that takes very little time. In each round, the candidate in last place is eliminated. Votes cast ranking that candidate first are then redistributed to those voters' second choices. That process repeats until there are only two candidates left. 

Today on AirTalk, we’ll get a preview of what’s at stake in today’s primary and find out more about how ranked choice voting works.

With files from the Associated Press

Guests:

Shelly Banjo, New York City bureau chief for Bloomberg; she tweets @sbanjo

Rick Pildes, professor of constitutional law at NYU school of law