With a rapidly growing campaign staff and a big investment in infrastructure, Bernie Sanders is going all in on the California ground game.

The Vermont senator’s campaign has opened five offices in California — far more than top rivals Sens. Kamala Harris and Elizabeth Warren, who have two each, and former Vice President Joe Biden, who hasn’t opened one. Sanders’ staff says they plan to set up at least 10 more offices by the end of the year and already have hired 40 full-time paid staffers in the state.

“We’re going to be running a ground game up and down the state of California like we’re Iowa,” said Jane Kim, Sanders’ California political director, in an interview at the opening party for the campaign’s new San Francisco office on Thursday. “We already have the biggest organization here, and it’s going to exponentially grow.”

It’s a potentially risky bet: Statewide campaigns here traditionally rely more on TV ads than knocking on doors to reach California’s millions of far-flung voters, in contrast to smaller states such as Iowa and New Hampshire. Sanders has also opened offices in East Los Angeles, San Diego, Fresno and Riverside — the latter two cities far off the typical itinerary for presidential contenders, but a sign of his campaign’s focus on growing the Latino base Sanders cultivated in 2016.

California election polls have shown Sanders narrowly trailing Warren and Biden but leading among young and Latino voters. Those groups have lagged in turnout in past elections, which means a large organizing campaign here could be especially helpful in driving his supporters to cast their vote.

“It’s a really smart investment for Sanders specifically,” said Mike Madrid, a GOP campaign strategist in Sacramento and an expert in California’s Latino vote. “Of all the candidates that could build a big organization here, he’s probably the one who would yield the biggest return.”

With just over 100 days before California’s March 3 primary — and even less before mail-in ballots start going out on Feb. 3 — the top campaigns are starting to build out their Golden State teams. Several presidential hopefuls are descending on Long Beach this weekend for the state Democratic convention, although Biden and Warren are sitting it out.

But despite California’s massive trove of 495 delegates and its new prominent presence earlier in the primary, it’s an open question how much the candidates will invest in time and money here over the next few months. The closely-watched South Carolina primary takes place just three days before California’s. And voters in more than a dozen other states will go to the polls on the same day — Super Tuesday — including Texas, Massachusetts, North Carolina and Virginia.

Only a handful of the 2020 contenders have any presence in California so far. Home-state senator Harris has opened offices in Oakland’s Grand Lake neighborhood and in Los Angeles, hosting a steady routine of phone banking events to call voters elsewhere in the state and around the country.

But her campaign has refocused on Iowa amid flatlining poll numbers, moving resources and staff to the Hawkeye State. Cuts and upheaval have hurt morale and provoked internal conflicts among Harris’ top aides, Politico reported Friday. A spokeswoman declined to comment about the campaign’s current California headcount.

Warren also recently opened an office in Oakland’s Chinatown neighborhood and also has one in Los Angeles. The campaign announced hiring nine staffers in the state this week.

Former hedge fund chief Tom Steyer based his campaign headquarters in his hometown of San Francisco and has recruited 27 staffers around the state for California-specific organizing jobs, a spokeswoman said. The campaign is planning to open other offices elsewhere in the state as well.

None of the other candidates appears to have any California offices open yet, according to a Bay Area News Group survey, although several said they are beefing up staff. A Biden spokesman said the campaign has five staffers in California and several others based elsewhere who are helping organize in the Golden State. The campaign is in the process of finding an office in the Los Angeles area, he said.

South Bend Mayor Pete Buttigieg also has hired five staffers in California, a spokeswoman said, with plans to open offices in the future.

Other campaigns insist they aren’t ignoring California. Sen. Amy Klobuchar’s campaign doesn’t have any staff or offices here yet, but organizers in her Minneapolis headquarters have worked to recruit volunteers in California, a spokeswoman said. Klobuchar drew a crowd of several hundred to a speech in San Carlos on Thursday, in advance of an appearance at the convention.

Bill Carrick, a veteran Democratic strategist in Los Angeles who isn’t working for any presidential campaign, said that California’s vast scale makes it difficult for all but the largest organizing campaigns to make a real impact. And he said it makes sense that most contenders are holding off before dropping money on staff here.

“Everyone’s scared to death that they’re going to invest in California when they don’t know if they’re even going to be around by election day,” he said.

The California race will certainly be shaped by what happens in the early states, and there are other wild cards that could come into play, such as former New York City Mayor Michael Bloomberg jumping into the crowded field. Bloomberg — a former Republican and independent — could reshape the contest by dumping huge sums of money on TV ads.

Meanwhile, Sanders is hoping to build on his support from the 2016 presidential race, when he narrowly lost California to Hillary Clinton.

His new office in San Francisco’s Mission District — previously an imported rug store that closed because of the Trump administration’s sanctions on Iran — will serve as his Bay Area headquarters. Volunteers will gather there four nights a week to call voters and use it as a home base to knock on doors around the region.

At an opening party on Thursday night, 200 people packed into the long space, which was decorated with campaign signs in Spanish, Chinese, Vietnamese and Tagalog. Organizers encouraged the Bernie fans to talk to friends and family about the senator over Thanksgiving and urged them to scan QR codes posted on the walls to sign up for volunteer opportunities on the campaign’s website.

Marina Perez, a 35-year-old chemist who works in San Francisco, said she voted for Sanders in 2016 but regrets not making the time to volunteer on that campaign.

“Knowing that the office is right here makes it a lot easier to get involved,” Perez said. “I’m ready to help out.”