The race to succeed Gov. Gavin Newsom of California when his second and final term ends in 2027 has officially been underway for years. One Democrat announced her campaign in April 2023, and the first debate was held in San Francisco in September 2024.

But really, the starting gun went off at noon sharp on Wednesday. That’s when Kamala Harris announced she would not run.

Almost immediately, the political landscape in the nation’s most populous state was upended.

Democrats in down-ballot races exhaled, knowing that dropouts from the governor’s race would not pose a sudden challenge for them. California political contributors took a fresh look at the prospects. Fund-raising emails tried to capitalize on the media attention. The will-she-or-won’t-she limbo that many of the Democratic candidates found themselves stuck in was over.

“I got, like, eight texts in the last two minutes,” said one candidate, Antonio Villaraigosa, a former mayor of Los Angeles, moments after the announcement. “This helps everyone, because now we know who’s in the field and who’s not.”

Still, for all the jostling, the contest seems to have pivoted from one middle ground to another.

Had Ms. Harris decided to run for governor, she would have catapulted the race onto the national stage, drawing supporters, detractors and megadonors to a contest that has so far been off the radar. Now that she’s out, a lengthy list of lesser-known political figures will duke it out, some of them unfamiliar even within California. With a crowded field of at least 10 candidates vying to be the next governor, the undercard is suddenly the main event.

“We could end up with more of a snoozer of a race than we’ve been accustomed to in recent elections,” said Brian Brokaw, a Democratic strategist who advised Mr. Newsom on his 2018 campaign for governor and Ms. Harris on her 2016 campaign for the U.S. Senate. He added, “Nobody comes into the race with a big advantage at this point.”

The contenders, naturally, see things far differently.

Some of the Democratic candidates were careful in their remarks to be respectful of Ms. Harris while also casting her decision as a good thing for their campaigns. Some had debated stepping out of the race if she decided to run, while others had made it a point to say publicly that they would run whether she was in or out.

Katie Porter, a former congresswoman from Orange County, sent out a fund-raising email on Wednesday, a little over an hour after Ms. Harris’ announcement. The Harris decision meant “we’re the clear frontrunner in this race,” the email read, “but I need your help to win.”

In an interview, Ms. Porter said Ms. Harris’s absence will help candidates keep the campaign focused on the future, rather than on the former vice president’s defeat in the 2024 presidential race.

“It helps people focus on what comes next,” Ms. Porter said. “It raises the momentum on the fact that this race is coming.”

Ms. Harris’s next move has been the topic of intense speculation. She began exploring a run for governor in January, when she returned home to Los Angeles after President Trump’s inauguration. As the months passed, pressure on her to make a decision mounted, even from sympathetic supporters. California is huge, both in geography and in population, and statewide races are breathtakingly costly and time-consuming. The clock was ticking, but the contest seemed to stand still while Ms. Harris weighed her decision.

“The race is now officially unfrozen,” said Dan Schnur, a longtime political analyst who teaches at the University of California, Berkeley, and the University of Southern California. “Even though the existing candidates have been raising money and campaigning and doing all the things candidates do, until Harris made her decision, they were just running in place.”

On Thursday, Ms. Harris announced on social media that her new book will be available on Sept. 23. She described the book, called “107 Days,” as a “behind-the-scenes look at my experience leading the shortest presidential campaign in modern history.”

None of the candidates now running for governor have Ms. Harris’s celebrity or her roster of volunteers and donors, but many of them have experience in public office.

Along with Ms. Porter and Mr. Villaraigosa, who is also a former speaker of the state Assembly, the Democrats include Lt. Gov. Eleni Kounalakis, who announced her campaign in 2023; Xavier Becerra, who served as the health and human services secretary in the Biden administration; Toni Atkins, a former legislative leader; Tony Thurmond, the state schools superintendent; Betty Yee, a former state controller; and Stephen Cloobeck, a real estate developer. Republicans in the race include Chad Bianco, the Riverside County sheriff, and Steve Hilton, a former Fox News host.

Ms. Porter is probably the best-known of the Democrats, from her frequent appearances on cable news shows and the viral moments she created in Congress, grilling executives with her white board. If Ms. Atkins wins, she would become the state’s first openly gay governor. Ms. Kounalakis has longstanding ties to the national Democratic Party as well as a family fortune.

Mr. Villaraigosa is pitching himself as a business-friendly Democrat willing to challenge his own party, while Mr. Becerra is leaning on his story as the son of immigrants who attained the American dream, and as the California attorney general who sued Mr. Trump more than 100 times during the president’s first term. Either Mr. Villaraigosa or Mr. Becerra would be the first Latino governor since the late 1800s, in a state where Latinos make up a plurality of the population.

One of the state’s top Democrats, former House Speaker Nancy Pelosi, has already said who she’s backing. When she was asked on CNN Wednesday about Ms. Harris’s decision, Ms. Pelosi used the opportunity to endorse Ms. Kounalakis, whose family she has known for decades. Ms. Pelosi telegraphed her fondness — and complicated the public’s recognition of Ms. Kounalakis — by referring to her by her maiden name, Tsakopoulos.

Whoever succeeds Mr. Newsom will take the helm of a state facing deep problems.

The state budget is forecast to run billions of dollars in deficits over for the next few years, which will probably require cuts to popular programs and services. Mr. Trump is targeting California with an aggressive push to deport undocumented immigrants and unravel the state’s progressive environmental and education policies, putting the state’s leader in constant conflict with the White House.

Californians are pessimistic about their economic circumstances, with surveys showing deep concern about the state’s high cost of living and shortage of affordable housing. Sixty percent of adults in a Public Policy Institute of California poll last month said the state was headed in the wrong direction.

California has not elected a Republican to statewide office since Arnold Schwarzenegger was re-elected governor in 2006. Many Republicans relished the thought of Ms. Harris running, seeing her as an opponent they could use to generate donations from across the country. Her withdrawal means the race is less likely to stir much interest from Republicans elsewhere in the country.

Mr. Hilton, one of the Republican candidates, said that was not a bad thing.

“I want the race to be focused on California, because that’s where it’s so obvious we need change,” he said in an interview, citing the state’s poverty rate and its high cost of housing.

The primary for governor — in which the top two candidates, regardless of party, will advance to the general election — is scheduled for June 2026, and there is still time for a wild card to scramble the race. One of those potential wild cards is Rick Caruso, a billionaire developer who spent more than $100 million in 2022 on an unsuccessful run for mayor of Los Angeles.

Mr. Caruso has indicated in recent years that he might try for mayor again, challenging Mayor Karen Bass next year, or he might consider a bid for the state’s top office. People close to him, however, say he might just as easily remain on the sidelines.

Mr. Caruso did not return calls seeking comment.

Ms. Harris’s decision leaves California with an unfamiliar feeling at the top of its ticket — a sudden lack of celebrity in a star-studded state. For most of the 21st century, the state’s governors have been well-known figures who used the office to advance themselves on a global stage: Mr. Schwarzenegger. Jerry Brown. Mr. Newsom.

On the other hand, some observers called the new field refreshing — and perhaps a boon for Californians in other ways.

“It’s good for democracy,” said David Townsend, a longtime political strategist in Sacramento. “And it’s good for political consultants. But it’s also good for democracy.”