California’s nearly 500 delegates to the Democratic National Convention next month will play a key role in choosing a replacement nominee now that President Joe Biden has ended his reelection campaign.

As they processed Sunday's thunderbolt announcement, some of them quickly fell in line with his wishes: End the drama and close ranks behind Vice President Kamala Harris.

“I feel this huge sense of relief, because it means the fighting is going to stop,” said Mike Thaller, chairperson of the California Democratic Party senior caucus, who was watching PBS’ “This Old House” when a friend called him with the news.

Following weeks of concerns about his cognitive health and public pressure to drop out, fueled by a disastrous televised debate performance in late June, Biden published a letter Sunday in which he acknowledged, “I believe it is in the best interest of my party and the country for me to stand down and focus solely on fulfilling my duties as President for the remainder of my term.”

Like millions of Americans, the Californians who are set to travel to Chicago in mid-August to select the Democratic Party’s nominee for president were in shock in the immediate aftermath of the revelation. But they told CalMatters that they are also excited about participating in a historic moment and hopeful that, after weeks of turmoil, Biden’s momentous decision — which included endorsing Harris as his replacement — could turn around Democratic prospects of stopping another term for former President Donald Trump.

“I don’t think it’s time to mess around,” said Brian Calderón Tabatabai, the mayor of West Covina who is also running for a state Assembly seat, recovering quickly from being “in a haze” after hearing the news on his way to brunch. “Right now is the time to show we as the Democratic Party have our things together, and this isn’t the chaos a lot of folks are making it seem.”

Sasha Renée Pérez, the mayor of Alhambra who is running for state Senate, said she hoped that Harris would help motivate voters who hadn’t been paying attention to the election before now, boosting fundraising and turnout in swing districts as Democrats also fight to regain control of the House in November.

“She comes from our home state. She’s a Black woman, an Indian woman. We’ve just never had anyone like her be our candidate,” Pérez said. “We have to get this show on the road and get her elected.”

Taking Biden’s signal, Democrats across the country — leaders of key caucuses in Congress, party activists, even former President Bill Clinton and 2016 nominee Hillary Clinton — quickly closed ranks behind Harris, dampening the prospects of an open convention in which delegates might choose from among a field of candidates after a flash primary.

California’s Gov. Gavin Newsom, who has been widely mentioned as a potential future presidential prospect, was slower to fall in line. Newsom released a statement praising Biden as an “extraordinary, history-making president,” but did not immediately endorse Harris, whom he had said in recent weeks that he would not run against.

His spokespeople did not respond for hours to questions about how he would like to see the party select a replacement nominee, though this afternoon, he eventually posted online that “no one is better to prosecute the case against Donald Trump’s dark vision and guide our country in a healthier direction” than Harris.

Also notably absent among the voices endorsing Harris was former House Speaker Nancy Pelosi, who reportedly played an outsized role in persuading Biden to drop out and told fellow California Democrats that there should be an open process to select a replacement.

None of the delegates who spoke with CalMatters said they had alternative candidates in mind, pointing toward a more likely competition to be Harris’ vice presidential pick.

“I’ll be surprised if anyone else gets into it,” said Sal Rosselli, president emeritus of the National Union of Healthcare Workers, calling Harris the “obvious choice to replace him.”

Harris drew criticism from left-wing critics during the 2020 primaries over her record as a prosecutor and California’s attorney general. Progressive activists and criminal justice reformers have criticized her handling of police shootings and called her record on the death penalty mixed.

But it wasn’t enough to dissuade progressive delegate Calderón Tabatabai. He called Harris “highly, highly ready to take over” for Biden and praised both for pushing a progressive domestic policy agenda, including efforts to expand workers’ rights.

“Those are issues,” he said of Harris’ record on criminal justice. “Are those issues something that would get me to say, ‘No, I’d like to see someone different at this point?’ Not now. Not when I understand what Project 2025 is,” he said, referring to the conservative policy wish list for a second Trump term.

Igor Tregub, a city councilmember in Berkeley who supported progressive Sen. Bernie Sanders in the 2020 presidential primaries, said he was won over by how much the Biden-Harris administration accomplished during the past four years.

“I have seen how hard she works every single day on so many issues that I as a Democrat care about,” Tregub said. “I am ready to work at 200% to support her and whoever she picks as her vice presidential candidate.”

Most delegates who spoke with CalMatters emphasized how the party should avoid the drama and contention of an open convention, especially in light of Biden’s endorsement.

“Democrats need to focus on what we’re bringing to the table for working families and Americans, and [the convention] not being a circular firing squad,” said political strategist Bill Wong. “I don’t care who the nominee is at this point, as long as we have a plan to hold the White House in November.”

In addition, there would be particularly challenging optics of passing on Harris, a mixed-race Black and Indian American woman, who was selected as Biden’s vice president partly as an acknowledgement of the crucial role Black women voters play in the Democratic coalition.

“Obviously we want to respect and support the people who helped get us here in 2020, and that’s Black women. We shouldn’t forget them,” said Dan Kalmick, a city councilmember in Huntington Beach.

Some delegates were more optimistic about the state of the race with Harris’ apparently easy path toward the nomination, citing her forceful statements supporting reproductive rights as a way to win women voters in swing states and the fact that she’s significantly younger than former President Donald Trump.

“Republicans have spent months telling voters the Democrats had an old guy running, and that boomerang just hit them,” longtime Democratic strategist Bob Mulholland said. “Harris should challenge the old man Trump to a 100-meter race to settle this.”

No delegates interviewed by CalMatters disagreed with Biden’s decision, and several praised him for eventually deciding to do what he believes is best for the country and not just himself.

“I know this decision cements his legacy,” Tregub said. “History will judge him kindly for his long and meaningful history of in so many ways advancing not just the best of what the Democratic agenda has to offer, but the best of America.”