San Francisco Assemblyman David Chiu and two members of the city’s Board of Supervisors endorsed Sen. Elizabeth Warren for president Thursday.

Chiu joined San Francisco state Sen. Scott Wiener in backing Warren after previously supporting California Sen. Kamala Harris for the Democratic presidential nomination. Chiu’s endorsement came the same day Mayor London Breed, who also supported Harris until she ended her campaign last month, endorsed former New York Mayor Mike Bloomberg.

Chiu said he is backing Warren because the Massachusetts senator “reflects the shared progressive values of San Francisco. She understands the issues that we are facing” — especially the lack of affordable housing — “and is offering ideas that are both bold and inclusive.”

Chiu attended Harvard Law School while Warren was teaching there, but did not know her. However, he said, he had heard from former classmates after Harris dropped out, encouraging him to support Warren.

He also said he had heard from Asian-Pacific Island community members who work on Warren’s campaign — something he said resonated with him as chairman of the California Asian & Pacific Islander Legislative Caucus.

Chiu said he had been “all in for Harris,” but when her campaign died, he realized that “this race is too important to sit out.”

Warren said in a statement that she is grateful to have the support of Chiu, someone “who has put the epidemic of homelessness on the front lines across California and given a voice to communities that far too often are underrepresented.”

Also on Thursday, San Francisco Supervisors Rafael Mandelman and Shamann Walton endorsed Warren.

Joe Garofoli is The San Francisco Chronicle’s senior political writer. Email: jgarofoli@sfchronicle.com Twitter: @joegarofoli