Three years ago, news of the end came at the municipal airport in Santa Monica. Bernie Sanders had parachuted into California dozens of times in a last-ditch effort to keep his presidential ambitions alive. But even as the Democratic-Socialist-turned-Democratic contender promised supporters gathered in an aging airline hanger that he would “continue to fight,” his self-styled “revolution” was effectively over.

The Sanders camp had hoped a win in delegate-rich California would bolster the candidate’s standing ahead of a delegate fight at the Democratic National Convention. The Golden State loss crushed those dreams, as Hillary Clinton cruised to victory there and clinched the nomination.

That was the fate of Bernie the insurgent in 2016. Bernie 2.0 is preparing for next year’s election as the ideological trailblazer of the newly insurgent left and an unlikely frontrunner in the Democrats’ large presidential field. To avoid being caught short in California again, Sanders has is making a concentrated and early effort there. Jeff Weaver, who managed the Vermont senator’s campaign in 2016, told reporters this week that the candidate will be prepared to compete in California and across the country.

“While in 2016 we had to make choices about where we could compete, I’m certain that in this race that some of our other opponents will have to make similar difficult choices,” he said. “This campaign will have the resources and volunteer strength to compete in every single state in the primary process.”

Part of this is simple necessity. Although California is fellow candidate Kamala Harris’ home state, the move of the primary from June to March has made it impossible to ignore. Instead of playing its traditional role as the final battleground – and sometimes an irrelevant one -- the Golden State will serve as “the gatekeeper” this time around, predicts veteran California pollster Paul Mitchell.

“If a candidate doesn’t do well in the early primary states but wins California, they get to April. Period. No questions,” Mitchell told RealClearPolitics. The inverse is also true. “If someone does well in Iowa and New Hampshire but doesn’t do well in California,” he continued, “other candidates could swamp them.”

California’s early influence is also enhanced by its emphasis on early voting. Voters are automatically registered and can vote by mail, an option that two-thirds of the electorate took advantage of in 2018. Mitchell expects turnout in 2020 to top 20 million -- with 16 million of those votes cast through the post office. Those ballots will be made available on Feb. 3, the same day Iowa Democrats go to the caucuses for their first-in-the-country contest.

According to analysis from Mitchell’s nonpartisan firm, Political Data Inc., this means California will start making its decision long before the race officially begins. Five percent will have voted by the time Iowa tabulates results, over 25 percent by the end of the New Hampshire primary, and a whopping 40 percent when the South Carolina contest concludes.

This means that California won’t be a sprint so much as it will be a month-long slog favoring the candidate with the best ground game and the most resources to put it into action. And this favors Harris, in particular. California’s freshman senator enjoys home field advantage.

One of her advisers, Averell Smith, told David Axelrod as much during a podcast last fall. He said that the early California primary with its early voting would be “a fun thing.” History may call it the key to Harris’ 2020 strategy if she wins the nomination.

“So the day Iowa votes,” the Obama former top strategist said, “California will begin voting, and that should be an enormous advantage to a candidate who is from California, which will have about what, 12 percent of the delegates?”

A Harris head start isn’t insurmountable, and there are signs Sanders is the candidate beat. The Harris campaign announced a $12 million fundraising haul in the first quarter, a sum raised from 218,000 individuals around the country. But Sanders took in $18 million from 525,000 unique donors – and, as his campaign gleefully informed reporters, 167,000 of those contributors call California home.

What’s more, as Mitchell notes, California is hardly a monolith. The pollster expects different candidates to target to different chunks of the electorate to keep the race tight.

Entrepreneur Andrew Yang will try to appeal to the tech sensibilities of Silicon Valley. Openly gay South Bend Mayor Pete Buttigieg will make a strong pitch to LGBT communities, especially in San Francisco. Former HUD Secretary Julian Castro will court Latino voters throughout the state. Eric Swalwell, a Democratic congressman from the San Francisco Bay Area, is toying with his own run. Above all towers former Vice President Joe Biden, who has not yet declared but who has national name recognition surpassing that of Harris and Sanders.

With the California contest being billed as the battle royale of the 2020 primary, influential players are remaining mum. Sen. Dianne Feinstein, Harris’ fellow home-state Democratic senator, insists she isn’t paying attention to Sanders’ recent visit and hasn’t been tracking his efforts to win the state’s 55 delegates.

“I haven’t heard about it so I can’t respond,” she told RCP.

Asked if she thinks, as California’s junior senator, Harris should be more competitive than Sanders in her own state, Feinstein said Harris would give him a run for his money.

“She will be competitive in California,” she said. “I have no doubt about that.”

Pressed further as to why Sanders has so many donors in the state -- nearly three-fourths the number of Harris’ -- Feinstein demurred: “Oh, I’m not going to get into any of that now — good try.”

That coyness may be indicative of a previous loyalty. Earlier this year, Feinstein said it would be difficult not to support Biden if he runs for president in 2020.

“I worked with him, I saw him in action, I saw him as vice president, I saw his growth, his ability and I saw his humanity,” the five-term senator told reporters in January. “He’s an incredible human being. It’s very hard for me, if he runs, to ignore that.”

Asked about Harris, Feinstein said, “I love Kamala. But this is a different kind of thing.”

The race will certainly be a different kind of thing, thanks to the new California schedule and a field that has moved farther left than any other in recent memory. While focus will shift to the early primary states, politicos and pollsters admit that the political gaze will remain fixed on the Golden State and its delegate windfall.

Some still shy away from describing California as the Holy Grail of 2020. Virginia Sen. Tim Kaine, Clinton’s running mate in 2016, acknowledged the outsized role the state can play but urged caution. “It’s important,” Kaine said, “but you can do well in California and not so well elsewhere — that’s why it’s wide open.”

To avoid a repeat of his last loss, though, Sanders has established an early beachhead in the state. It could be key to keeping his second “revolution” rolling.

Susan Crabtree contributed to this report.