The phone call to London Breed came Wednesday morning from Mark Leno's office.
VIDEO: Here's how ranked-choice voting works
"I called Supervisor Breed this morning to congratulate her on her victory and to wish her every success," said Leno.
The 66 year-old former State Senator said while he initially led the race a week ago, eventually his numbers eroded, with Breed pulling ahead.
"We haven't seen a day that it hasn't gone in her direction. We are now done to fewer votes than we had a week ago," Leno said.
MEET THE CANDIDATES: Mark Leno
Once the results are certified by the Department of Elections, 43 year old Breed will become the city's first African American woman to be mayor of San Francisco. The earliest day she can assume office is July 10.
Supervisor Jane Kim who was also running for mayor congratulated Breed. A month ago, both Leno and Kim had formed an alliance asking their supporters to vote for them as their first and second choices-hoping one of them would defeat Breed - a strategy that has worked in other races as part of the rank-choice voting system. In this case it did not work.
MEET THE CANDIDATES: London Breed
"The campaign is over and it is time for us to forget about the drama that existed in the world of politics during this campaign and it's time for us to focus on addressing the challenges ahead so that we can make our city better for all San Franciscans," Kim said.
Breed will have to run in the November 2019 election for a four-year term.
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