There’s nothing surprising about a billionaire winning the support of the mayor of San Francisco, a city flush with tech wealth and new money.

But when the billionaire is Mike Bloomberg – and the endorsement is the latest from a string of California mayors he mentored and supported – the vow of support raises some eyebrows.

Bloomberg announced on Thursday that London Breed, San Francisco’s first black female mayor, would serve as his campaign’s chair of African Americans.

London Breed. Photograph: Eric Risberg/AP

“Voters re-elected London Breed by a wide margin because she is taking on the biggest and toughest issues – and she puts progress over politics,” the former New York mayor said in a statement. “I’m honored to have her support and look forward to working with her not only to win this election, but to help make San Francisco and all of California stronger, fairer, and greener – with more affordable housing, more good jobs, and healthcare for all.”

Breed, who previously supported the California Senator Kamala Harris in the Democratic race for the presidential nomination, said on Facebook that she is backing Bloomberg because he “is the only candidate for president with a real plan for African Americans”, touting his Greenwood Initiative to increase black home ownership and the number of black-owned businesses.

She acknowledged his harmful legacy of stop-and-frisk, the policing strategy that led to widescale racial profiling in New York City when Bloomberg was mayor, saying Bloomberg “owned up” to his “mistake” when he apologized for the 12 years he allowed the policy to flourish.

“Of course I was a bit surprised to see the mayor endorsed Bloomberg,” said Lateefah Simon, president of the Bay Area Rapid Transit board and longtime friend of Breed. “But herein lies the power of the individual. It’s not San Francisco endorsing Mayor Bloomberg. It’s Mayor Breed.”

For some in San Francisco, that’s the problem. “I haven’t met many Bloomberg supporters in San Francisco,” local lawmaker Matt Haney told the Guardian. “In fact, I don’t think I’ve met any. It doesn’t seem reflective of where the residents of San Francisco are. I don’t think her endorsement is reflective of how residents feel.”

A recent UC Berkeley poll found that 85% of Californians have either a negative opinion of Bloomberg or no opinion at all. Yet since entering the race late in November, Bloomberg has secured the endorsements of the mayors of three major cities in the state – San Francisco, Stockton and San Jose. “I haven’t met any Bloomberg supporters who were not elected officials, period,” Haney said.

Bloomberg, one of the richest people in the United States, has for years invested in developing political and support network for local leaders, providing them access to both money and expertise. All three California mayors who recently announced endorsements went through Bloomberg’s Harvard City Leadership Initiative, a training program for city mayors – Stockton mayor Michael Tubbs and San Jose mayor Sam Liccardo in 2018, and Breed in 2019. Tubbs attended the CityLab Summit in Paris in 2017, another Bloomberg-sponsored conference.

In San Francisco, Bloomberg’s support included a $275,000 donation to support a soda tax and $7.1m to defeat an initiative to reverse a ban on e-cigarette sales – both measures supported by Breed. In 2018, San Jose received up to $2.5m from Bloomberg Philanthropies to tackle climate change. In June, Bloomberg Philanthropies donated $500,000 to a Stockton-based education reform group.

“Mike has made significant investments in San Francisco, in cities throughout California, and indeed across the nation,” Breed said on Facebook.

It’s significant that Bloomberg has been able to win the endorsements of black trailblazing mayors like Tubbs and Breed.

At his first campaign stop in Stockton, California, in December 2019 Bloomberg stood next to Tubbs and apologized again for stop-and-frisk, but never acknowledged why the policy was harmful, or who it harmed.

“There isn’t a politician alive who hasn’t made a mistake,” Breed said of stop-and-frisk. “The difference with Mike Bloomberg is he owned up to his.”

“I think there is a long track record of people reaching out to black leaders and black communities in transactional ways,” Alicia Garza, founder of the Black Lives Matter movement, told the Guardian. “It really represents a lot of what’s wrong with politics in this country and I think it’s hard to believe that change will happen when these same kinds of dynamics are at play.

“With that being said,” she continued, “there are decisions that leaders are having to make and they’re doing the calculus. Every leader has a right to do that.”

Garza’s group, Black to the Future Action Fund, will be announcing its endorsement in February. While she demurred on her thoughts on Bloomberg and stop-and-frisk, she made a point to say that the group will consider “not just [the candidates’] future plans, but interrogating their records since they’ve been in power”.