With President Biden dropping out of the presidential race, California is poised to play a critical role in selecting a new Democratic nominee. The state is home to the most delegates for the Democratic National Convention — and to Vice President Kamala Harris, a former U.S. senator who has a house in Los Angeles.

Within hours of Biden endorsing Harris on Sunday, California’s Democratic leaders began working to lock the state’s 496 delegates down for the vice president. State Democratic Party Chair Rusty Hicks sent a form to delegates, asking them to endorse Harris.

“Now it is time for Democrats to unite around our common calling — defeating Donald Trump, retaking the House of Representatives and preserving our democracy,” Hicks said. “I am asking delegates from our great state of California and home to our Vice President, Kamala Harris, to officially endorse her nomination for President of the United States at the convention in Chicago.”

San Francisco Democrats, including Mayor London Breed, hastily organized a Monday morning rally for Harris on the City Hall steps.

The potential for California to flex its political muscle on the national stage follows a period of waning power for the Golden State.

For years, Californians enjoyed seats in the highest echelons of power — Rep. Nancy Pelosi (D-San Francisco) became the most powerful woman in congressional history as speaker of the House. Then came her Republican successor, Kevin McCarthy of Bakersfield. Sen. Dianne Feinstein of San Francisco became the longest-serving female senator in U.S. history and served on powerful committees.

But in quick succession over the last two years, California’s power slipped. Pelosi stepped down in 2022 to offer space for “a new generation” of Democratic leaders. McCarthy lost his speakership in a historic fallout with his own party, and then resigned from Congress. Feinstein died in September.

If Oakland-born Harris, who served as California’s senator and attorney general before she was vice president, becomes the Democratic nominee, a Californian would be a major party’s presidential candidate for the first time in decades.

Another Democrat could emerge to vie for the party’s nomination at the Chicago convention, but California’s bloc of delegates will be crucial for securing it. Already, several California political leaders quickly called for Democrats to support Harris — including Gov. Gavin Newsom.

“Tough. Fearless. Tenacious,” Newsom said in a statement on social media. “With our democracy at stake, and our future on the line, no one is better to prosecute the case against Donald Trump’s dark vision and guide our country in a healthier direction than America’s Vice President.”

Newsom was widely considered as another potential replacement for Biden, though he repeatedly swatted down rumors of harboring his own presidential aspirations. The governor served as a surrogate for the Biden campaign, crisscrossing the country to stump for him — and raising his own national profile.

But as speculation mounted in recent weeks over Biden, Newsom made it clear he would not compete with Harris. “Of course,” Newsom said recently, when asked whether he stood by comments he made last year about not running against Harris. “Yes.”

California Sens. Alex Padilla and Laphonza Butler also threw their support behind Harris.

“This is a woman who has dedicated her entire career to public service,” Butler said in an interview Sunday. “This is a woman who has never … backed down from a fight.”

Notably absent from the list of Harris supporters Sunday was Pelosi, who applauded Biden as “a patriotic American who has always put our country first,” without mention of the vice president.

The former speaker reportedly fielded calls in the last several weeks from Democrats who were upset about Biden’s disastrous debate performance and fearful about his reelection chances. Pelosi told fellow California Democrats last week that she would prefer the party engage in an open process to select a new nominee, rather than automatically tapping Harris, Politico reported.

Rep. Jared Huffman (D-San Rafael) said he was confident Harris would become nominee, but that some Democrats are debating the best way for that to happen.

“You’ve got some national Democratic leaders who are very supportive of Kamala Harris but also feel strongly there should be some sort of process,” Huffman said.

Rep. Adam B. Schiff (D-Burbank), a close confidant of Pelosi’s and another California leader in Congress, immediately gave Harris his support. Schiff was the topmost congressional leader to call for Biden to drop out last week.

“She has the judgment, experience, leadership, and tenacity to take on and defeat Donald Trump,” Schiff said in a statement Sunday. “I worked with her when she was our Attorney General, Senator, and Vice President, and I can’t wait to work with her as President.”

Rep. Robert Garcia (D-Long Beach), who backed Harris’ presidential bid in 2020 and is on Biden’s national campaign committee, said he was “proud to support the vice president.”

“For California, especially, this is an incredible step forward and an incredible day,” he said. “I think the whole state and the party is unifying behind her and I think she’ll be the nominee within a couple of days.”

While the California political class is lining up behind Harris, the delegates could still be a toss-up. Steve Maviglio, a Democratic political consultant who is an alternate delegate from Sacramento, said the delegates he’s spoken to are unified in wanting to defeat Trump in November. The consensus, he said, is hope for “a seamless hand-off from the Biden campaign to the Harris campaign.”

“I don’t think there’s a lot of appetite for a mini-primary, four more weeks of turmoil,” Maviglio said. “We want to get this done, focus!”

Practically, he added, it would be impossible for another candidate to emerge and mount a proper fight against Trump in the next four months. Already, Biden’s campaign coffers are being transferred to Harris. As vice president, Harris also is already familiar with key Democratic donors.

“It’s weird in that people will look back and say ‘That’s historic.’ But you actually feel like you’re living history right now, and it’s a very peculiar feeling,” Maviglio said. “I just hope this doesn’t come back to bite us in our butt.”

Times staff writers Noah Bierman and Seema Mehta contributed to this report.