SACRAMENTO — Despite a plea from the head of the California Democratic Party for underperforming candidates to drop out of the governor’s race, all but one of the party’s top hopefuls spurned the request.

Party leaders fear the growing possibility that the crowded field will split the Democratic electorate in the state’s June top-two primary election and result in two Republicans advancing to the November ballot, ensuring a Republican governor being elected for the first time since 2006.

His advice largely unheeded, state party Chairman Rusty Hicks on Thursday said the fate of a Democratic victory now rests squarely on the gubernatorial candidates who flouted him.

“The candidates for Governor now have a chance to showcase a viable path to win,” Hicks said in a statement Thursday.

Eight top Democratic candidates filed the official paperwork to appear on the June ballot after Hicks released a letter on Tuesday urging those “who cannot show meaningful progress towards winning” to drop out. Friday is the deadline to file to appear on the primary election ballot. On March 21, the secretary of state’s office will formally announce who will appear on the June ballot.

“It sounded like someone who has his head in the sand,” former Los Angeles Mayor Antonio Villaraigosa said of Hicks’ open letter. “[Most] of us filed within 24 hours of getting that letter. It created some press but not much else. It didn’t impact [most] of the candidates and it certainly didn’t impact my candidacy.”

Democratic strategist Elizabeth Ashford said it was appropriate for Hicks and other Democratic leaders to make a public plea as opposed to keeping such discussions solely behind closed doors.

But the response showed the limited power of the modern-day party bosses.

“It’s definitely not Tammany Hall,” said Ashford, referring to the storied Democratic political machine that had a grip on New York City politics for nearly a century. “The party and Rusty are influential and they are helpful and that is their role. I don’t think anyone would be comfortable with outright public strong-arming of specific candidates.”

Ashford, who worked for former Govs. Jerry Brown and Arnold Schwarzenegger, along with former Vice President Kamala Harris when she served as state attorney general, added that the minimal power of the state GOP is likely a factor in the dynamics of Democrats’ decision to stay in the race. Democratic registered voters outnumber Republicans by almost a 2-to-1 margin in the state, and Democrats control every statewide elected office and hold supermajorities in both chambers of the California Legislature.

“If there were a strong viable opposition that existed, if the Republican Party was actually relevant in California, I think that would sort of force greater unity amongst Democrats,” she said.

Just one of the nine major Democrats did heed the party chair’s message. Ian Calderon, a former Los Angeles-area Assemblyman who consistently polled near the bottom of the field, withdrew from the race and endorsed Rep. Eric Swalwell (D-Dublin) on Thursday.

Candidates cannot withdraw their name from the ballot once they officially file to run for office, leading to some fears that even if other candidates drop out of the race, a crowded primary ballot could still split California’s liberal votes.

“I’m disappointed most of them will be on the ballot,” said Lorena Gonzalez, the head of the California Federation of Labor Unions, which will announce whether it endorses in the governor’s race on March 16. But “I do still think you can have people drop out of the race or become viable. I think that there are candidates who know viability is a real thing they have to show in coming weeks” before ballots start being mailed to voters.

Jodi Hicks, chief executive and president of Planned Parenthood Affiliates of California, said she is “still worried” about the prospect of two Republicans winning the top two spots in the June primary, shutting Democrats out of any chance of winning the governor’s office in November.

“I didn’t have any specifics of who I wanted to do what,” she said. “I’m just very, very concerned and the stakes are really high right now and seem to be getting worse by the day.”

Republican candidate Steve Hilton, a former Fox News host, said he is “confident that I’ll be in the top two” along with a Democratic candidate. “I find it very difficult to believe that the Democratic Party will just surrender California and allow two Republicans to be in the top two.”

Hilton made the comments Thursday after a gubernatorial forum in Sacramento hosted by the California Assn. of Realtors focused on housing and homeownership. Villaraigosa, former Health and Human Services Secretary Xavier Becerra, San Jose Mayor Matt Mahan and former Rep. Katie Porter also attended. Swalwell, who is currently in Washington, joined the panel virtually.

During the panel, candidates were in broad agreement about the need to reduce barriers and costs in order to build more housing in California, where the median single-family home costs more than $820,000. Many also endorsed proposals to disincentivize private investment firms from buying up homes as well as a $25-billion bond proposed by former Sen. Bob Hertzberg to help first-time homebuyers afford a down payment.

“This really isn’t a debate because we’re agreeing so much with each other,” Hilton said at one point during the event.

That political alignment on one of the most pressing issues facing California may explain why voters are having such a difficult time deciding who to support.

A recent poll of the Public Policy Institute of California found that the five candidates topping the crowded field were within 4 percentage points of one another: Porter, Swalwell, Hilton, Democratic hedge fund founder Tom Steyer and Republican Riverside County Sheriff Chad Bianco. Earlier polls had Hilton and Bianco leading the field, though many voters remained undecided.

Some candidates took issue with Hicks’ push to cull the field, noting that most of the lower-polling candidates he asked to drop out are people of color.

“Our political system is rigged, corrupted by the political elites, the wealthy and well connected,” state Supt. of Public Instruction Tony Thurmond, who is Black and Latino, said in a video posted on social media in response to the open letter. “The California Democratic Party is essentially telling every person of color in the race for Governor to drop out.”

Villaraigosa argued that enough voters remain undecided that it was too early for quality candidates to call it quits.

“Most people don’t even know who’s in the race,” said Villaraigosa. “It’s premature to be thinking about getting out of the race. I certainly am not considering it and I feel no pressure.”

Aside from the opinion polls, other indicators on who may emerge from the pack a candidates are slowly emerging.

Though it wasn’t enough to win the party’s endorsement, Swalwell won support from 24% of delegates at the state Democratic convention last month, the most of any party candidate.

While spending is no guarantee of success, Steyer has donated $47.4 million of his own wealth to his campaign. Mahan, who recently entered the race and is supported by Silicon Valley leaders, has quickly raised millions of dollars, as have two independent expenditures committees backing his bid.

Ashford said part of candidates’ decisions to remain in the race could have been driven by their lengthy political careers, as well as Democrats’ crushing November redistricting victory.

“In several cases, these are people who have won statewide office,” she said. “It’s tough to feel like there may not be a sequel to that.”

Nixon reported from Sacramento and Mehta from Los Angeles.