Steyer, a billionaire philanthropist and former California gubernatorial candidate, said in a social media post that both candidates were strong but that he was voting for Wiener. He described the state senator as “a tireless fighter for the city” and cited his work on climate change and lowering costs for Californians.

The endorsement could help Wiener appeal to progressive voters, a significant part of Chan’s political base. Chan campaign spokesperson Ian Krager responded that billionaires supporting Wiener was unsurprising, adding, “it is always nice to see the owners publicly endorse management.” Krager also pointed to Chan’s proposals on energy costs and utility reform.

Reich’s endorsement gave Chan a prominent ally known for criticizing concentrated wealth and corporate power. In a statement, Reich said the concentration of wealth in the United States had become a concentration of political power and argued that the divide was pushing San Franciscans out of the city.

Chan has made taxing billionaires a central part of her campaign message. She is backed by the California Federation of Labor Unions and the San Francisco Labor Council and is the only candidate in the race who supports Proposition 40, according to the campaign coverage.

The dueling endorsements offer voters competing signals about the candidates’ priorities as the contest for San Francisco’s congressional seat continues. Reich is a professor emeritus of public policy at UC Berkeley; he joined the university in 2006 and became emeritus in 2023. His social media accounts have a combined following of more than 10 million, according to the report.