<a href="https://www.nytimes.com/2019/12/24/us/politics/bernie-sanders-2020-california.html" target="_blank" rel="noopener noreferrer">How Bernie Sanders Learned to Love Campaigning in California</a>  <font color="#6f6f6f">The New York Times</font>

California is the linchpin of Mr. Sanders’s 2020 strategy, a state he hopes will turbocharge his campaign on Super Tuesday — or revive his candidacy if he underperforms in the early states.

Bernie Sanders made five public appearances in California last week, including a rally in Venice Beach.Credit…September Dawn Bottoms for The New York Times

LOS ANGELES — Four years ago, Marlene MacAulay experienced her political awakening during Senator Bernie Sanders’s first presidential campaign.

“Last time it was underground,” said Ms. MacAulay, a 68-year-old bookkeeper from Simi Valley, Calif., who is so committed to Mr. Sanders that she named her schnauzer Bernie. In 2016, she said, she joined ad hoc groups of local Sanders supporters that formed on Facebook.

It’s not underground anymore.

California, perhaps more than anywhere else, shows how the Sanders campaign has evolved from a movement of true believers into a strategic machine built to win a presidential nomination. As Mr. Sanders and his advisers look beyond the four early-voting states and toward Super Tuesday on March 3, they are making a big play to accrue as many delegates as possible from California, the biggest prize on the map.

It’s a striking change from what Jeff Weaver, a top Sanders aide, called the “run and gun” operation of 2016. That year, Mr. Sanders hoped to make a last stand against Hillary Clinton in California’s June primary, but took only 46 percent of the vote. His team wasn’t sophisticated enough to focus its efforts where it could claim a disproportionate number of delegates — he carried just eight of California’s 53 congressional districts — allowing Mrs. Clinton to increase her delegate lead and clinch the Democratic presidential nomination.

Now Mr. Sanders, of Vermont, has the most robust California organization in the 2020 field. He has 80 campaign staff members in the state, more than any other candidate. He has spent time wooing the sorts of local officials whom he once derisively cast as part of the dreaded political establishment. And no 2020 candidate has held more public events in California than Mr. Sanders, according to a count maintained by The Sacramento Bee.

California’s decision to move its primary from its 2016 slot, at the end of the nominating calendar, to March 3, three days after South Carolina completes the quartet of early-state nominating contests, means that the Golden State will have more influence than ever in picking a presidential nominee.

Just as South Carolina, with a majority-black Democratic electorate largely loyal to Joseph R. Biden Jr., is a firewall for the former vice president, Mr. Sanders is banking on California — either to resurrect his campaign if he underperforms in the early states or to turbocharge it if he reaches March with momentum.

For now, Mr. Sanders is poised to win a large share of California’s delegates. He has placed first or second in five of six public polls of the state dating back to mid-October. People close to the campaign predict he will come in first or second — and more critically, above the 15 percent threshold needed to accrue delegates — in every congressional district.

“We do believe that if we do well in California, which we are primed to do, that the delegate breakout from California can be the moment that you walk toward the nomination,” said Faiz Shakir, Mr. Sanders’s campaign manager.

The contrast between Mr. Sanders’s approach to California and that of his top opponents was stark in the days surrounding last week’s presidential debate at Loyola Marymount University in Los Angeles. Mr. Sanders made the most of his week in the state, appearing at five public events. Senator Elizabeth Warren of Massachusetts, Mr. Sanders’s leading left-wing rival, didn’t make any public stops outside of the debate.

Mr. Biden hosted two fund-raisers, posed for photos with striking McDonald’s workers and had lunch with a handful of voters at a Mexican restaurant. And Mayor Pete Buttigieg of South Bend, Ind., appeared at six fund-raisers and a Democratic National Committee gathering in the state before holding a pair of public events on Friday.

One of Mr. Buttigieg’s fund-raisers, at a wine cave in Napa Valley, was mocked by Ms. Warren during the debate and by top Sanders aides, who paraded past reporters in the spin room at Loyola Marymount wearing shirts reading “peteswinecave.com.”

Who’s in, who’s out and who’s still thinking.

Mr. Buttigieg spoke to roughly five times more people at the fund-raisers than he did at the public events, according to crowd estimates from pool reporters. (Reporters were not allowed to attend the wine cave event.)

The public events for Mr. Buttigieg were designed to show him being introduced to Latino voters and listening to their concerns. In Walnut, east of Los Angeles, Mr. Buttigieg received a warm introduction from the city’s 26-year-old mayor, Andrew Rodriguez. But Mr. Rodriguez clarified afterward that he hasn’t endorsed Mr. Buttigieg — he’s still thinking about Mr. Biden, too.

“I just relate to Pete because he’s a young mayor,” Mr. Rodriguez said.

Mr. Sanders, who polls show has a clear advantage with Latino voters in the state, stopped at the Mexican border on Friday night before holding a rally on Saturday with Representative Alexandria Ocasio-Cortez of New York that drew 14,000 people to Venice Beach.

“For most candidates, California is a piggy bank,” Mr. Weaver said as crews cleaned up after the rally. Mr. Sanders, he said, “doesn’t just come here and go to the wine cave — sorry, I had to — and then fly out to Iowa. He actually comes here and talks to voters.”

Mr. Sanders and his campaign are also doing the sort of spadework his 2016 campaign didn’t. He has opened offices in heavily Latino regions of the state and is doing the sort of outreach to local elected officials he resisted last time.

Nick Carter, the national political outreach director for the 2016 Sanders campaign, said it was “challenging” to get Mr. Sanders on board back then. “He was giving his time to voters and not just currying favor with politicians,” Mr. Carter said.

One of the officials Mr. Sanders courted this year was Reggie Jones-Sawyer, a state assemblyman from South Los Angeles. Mr. Jones-Sawyer had been an enthusiastic supporter of Mrs. Clinton in 2016 — a Little Rock native, he has deep roots with the Clintons — and had in May endorsed Senator Kamala Harris of California for the 2020 presidential nomination.

In November Mr. Jones-Sawyer took a meeting with Mr. Sanders on the sidelines of the California Democratic Party State Convention. Ms. Harris was still in the race, but struggling. Mr. Sanders made the pitch, and Mr. Jones-Sawyer told Mr. Sanders he was his second choice.

“Before she dropped out, Bernie Sanders was smart enough to come to me, talk to me personally,” Mr. Jones-Sawyer said at the Venice Beach rally, where he delivered one of the warm-up speeches for Ms. Ocasio-Cortez and Mr. Sanders. “Then, all of a sudden, it happened. She wasn’t in. And then, I reread his criminal justice plan and realized, for my district, South L.A., it works great.”

Javier Gonzalez, a Californian who was Mr. Sanders’s deputy field director for Western states in 2016, said the 2020 operation is far more professional. Four years ago the staff members were a combination of operatives the Clinton campaign didn’t want and true believers who had never been involved in politics before, he said.

“I would imagine Bernie had a lot more high-level applicants this time. We were making half the stuff up as we went along,” Mr. Gonzalez said, using a more pungent word than stuff.

Mr. Weaver, who was Mr. Sanders’s campaign manager in 2016, said the team learned many lessons that year that it is leaning on in this race.

“Having done this before really does matter, right?” Mr. Weaver said. “And there’s mistakes we made last time — I won’t delineate here — that we won’t make again.”

California, with 40 million people, has long been considered impossible to win through campaign organization and tactical spending alone. It’s too big and, with 15 media markets, too expensive to saturate with television advertising — though the billionaire candidates Tom Steyer and Michael R. Bloomberg seem poised to test that proposition this year.

Californians can vote by mail as soon as the day after Iowa’s Feb. 3 caucuses, meaning voters here might be influenced more by the results in the first four states than by any contact they receive from a campaign organizer or ads they see on TV.

That’s why senior California Democrats, who acknowledge Mr. Sanders has the premier presidential team in the state, scoff at the idea that his organization can save him if he performs poorly in the early states.

“All that momentum that comes out of Iowa and New Hampshire, I think, still is so determinative,” Gov. Gavin Newsom said. “Let me tell you, as someone who’s run multiple times statewide, there’s still no substitute for momentum, still no substitute for generating energy on the nightly news.”

But Mr. Sanders’s investment in California appears to be paying some dividends.

Ms. MacAulay, who is volunteering to knock on doors and make phone calls for Mr. Sanders, said she got several text messages inviting her to attend the Venice Beach rally. “Last time not as many people knew about Bernie,” she said. “It’s more organized now. He taught us how to do it.”

Interviews at the rally revealed that while die-hard fans populated the grassy knolls surrounding the stage, the seating sections up close had a number of people who were new supporters.

Mamak Khadem, a 58-year-old trance music singer from nearby Santa Monica, said she had never voted since becoming a United States citizen three decades ago. But after seeing Mr. Sanders at an event in July, she joined a group of local Iranian-Americans supporting his campaign.

“I never felt connected to any of the candidates running before,” she said. “But everywhere Bernie has been, he’s been so accessible.”