EMBED >More News Videos San Francisco has been using ranked-choice voting since 2004. Here's how it works.

SAN FRANCISCO (KGO) -- At least for the next several days, the San Francisco Department of Elections will have updated results on the mayoral race 4 p.m. daily. Less than a percentage point separates the top two candidates: Mark Leno with 50.42 percent of the vote and London Breed with 49.58 percent.But the ballots keep coming in. Those postmarked on or before election day are valid as long as they arrive by Friday."So today we received 13-thousand, almost 13-thousand of such ballots. We checked the postmarks and most of those ballots have good postmarks on them so that's another 13,000 ballots that we didn't have yesterday that we have today," said John Arntz, San Francisco's Director of Elections.San Francisco Department of Elections starts fresh every day, counting the entire batch of ballots all over again.According to the latest count, roughly 75 percent of Jane Kim's voters chose Mark Leno as their second choice, while 25 percent chose Breed -- a difference that's pushing Leno slightly ahead despite Breed having captured the most first-place votes in the first round.No surprise that one day after the election, the candidates have different views on the instant runoff system called ranked choice voting."This is the one we're dealing with as it relates to this race so, for now, we're stuck with it," said Breed."It promotes more positive campaigning because if I want your second place votes I'm not going to drop a bomb on you and so I think we saw that in this race as well," said Leno.San Francisco State Professor and Political Analyst Joe Tuman went through ranked choice voting twice as a candidate for Oakland mayor."It does feel a little bit unfair when you have the most number of first place votes and you end up not winning because you didn't get seconds and thirds, but arguably if you want to be everybody's candidate then you need to get more than 50 percent of the first place votes and never have to deal with ranked choice," said Tuman.But at this point, the race is too close to call -- and is expected to take days if not weeks to determine the winner.