SAN FRANCISCO (AP) — Business community favorite London Breed was leading in the race for San Francisco mayor in a competitive race that may not be declared Tuesday.

Breed's two fiercest competitors and more liberal Democrats, Mark Leno and Jane Kim, were trailing in second and third place.

Breed, 43, would make history as the city's first African-American female mayor. The president of the Board of Supervisors was raised by her grandmother in San Francisco public housing, graduated from public schools and is touted as a local success story.

"There's still a lot more votes to count. Everyone has cast their ballots and all we can do is wait and see," Breed told supporters Tuesday night. "But I feel good inside."

San Francisco is an expensive city with a healthy economy thanks to the tech industry, but homelessness remains an entrenched issue and residents are cranky over filthy streets and traffic gridlock.

San Francisco uses an unusual ranked-choice voting system in which voters select their top-three favorites. The candidates with the least votes are eliminated in rounds until there's a winner.

Breed had about 36 percent of the vote with 123,000 ballots counted Tuesday night.

Leno, a former state senator who would make history as the city's first openly gay mayor, was in second place with 26 percent of the vote. Kim, a San Francisco supervisor and daughter of Korean immigrants, had 21.5 percent.

Dozens of people waited in long lines in San Francisco's City Hall on Tuesday, waiting to vote for a new mayor. Mayor Ed Lee died unexpectedly in December, bumping up a race that was not supposed to be held until next year.

Adrian Baker-Kang, 25, said he was still undecided on who to pick for mayor, even as he prepared to get in line to vote. The Democrat recently moved back to San Francisco after years abroad as part of the Peace Corps.

"I feel personally I align with London Breed and her policies a little bit more. I like what she stands for, I like who she is, but I feel like in today's political climate, Leno is a little bit less divisive," he said. "I think he's a more relatable, approachable figure."

But Alyssa Sewlal, a 32-year-old Democrat who works for a public policy nonprofit, voted for Breed partly because she has received support from former Republican President Ronald Reagan's secretary of state, George Shultz.

"There's nothing wrong with her getting support from both sides," she said.

All three are Democrats, but Breed is backed by the establishment business community while Leno and Kim are favored by more liberal elements of the party, including tenants and critics of tech companies such as Airbnb and Uber.

A fourth candidate, Angela Alioto, served as a supervisor in the late 1980s and 1990s and her father, Joe, was mayor from 1968 to 1976. She was in fourth place.

In California, ballots postmarked by June 5 and received by Friday are accepted. John Arntz, the director of the Department of Elections in San Francisco, has said a winner might not be known for days.

In 2010, Jean Quan became the mayor of nearby Oakland when she scored enough second- and third-place votes to beat the candidate with the most first-place votes.

In this race, Kim and Leno are deploying a similar tactic and have asked supporters to vote for the other as their No. 2 choice on the ballot.

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This version corrects the spelling of San Francisco elections director John Arntz.

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Associated Press writer Lorin Eleni Gill contributed to this report. Sign up for "Politics in Focus," a weekly newsletter showcasing the AP's best political reporting from around the country leading up to the midterm elections: http://apne.ws/3Gzcraw