The vast state’s reputation for a lengthy vote-counting process could prevent the quick emergence of a winner that night. But Padilla maintains there’s little danger that the confusion of Iowa will happen in California, in part because the state’s elections are overseen by state administrators, not party officials. Plus, he argued, “the biggest issue in Iowa was the use of an app — and California does not use apps’’ for counting or casting ballots, or for reporting results — and the state “doesn’t allow the voting system to touch the internet” to prevent hacking.

But political veterans here note that the complex, costly political landscape of the Golden State, including more than a dozen major media markets, does present a daunting series of campaigning hurdles for contenders. Democratic delegates in each of the 53 House districts will be doled out proportionally — and a candidate must meet a threshold of 15 percent of the district’s voters to come away with any delegates at all, a hurdle that veteran state voting expert Paul Mitchell calls a potential "killer" for struggling second-tier candidates.

California is “incredibly expensive from a media perspective — cost-prohibitive for some of the campaigns,’’ notes Buffy Wicks, who helped run Barack Obama’s 2008 grassroots campaign here and directed Hillary Clinton’s 2016 California effort. That means “to build an effective field program you really have to start, like, last year,’’ says Wicks, now an East Bay assemblywoman.

That hasn't deterred a late, all-out entry into the California primary fight by billionaire Bloomberg, who had the delegate-rich California terrain all to himself earlier this week as the rest of the Democratic pack arm-wrestled for the 49 delegates — just 10 percent the size of California’s delegate take — that will ultimately be awarded in snowy Iowa. Bloomberg appears ready to seize on the confusion and campaign shakeups that emerged from Iowa, and Biden’s under-performance — and California looms large in that effort.

“Having California moved up is obviously an important part of this whole process. The sheer size and magnitude of the campaign here is a critical part and our ground game — and what we’re doing in the state here is pretty extraordinary,’’ says veteran Democratic strategist David Chai, who serves as a Northern California political director for Bloomberg.

His team is pouring money — and time — into the state, blanketing the airwaves with $13 million in ads since the start of the year and sending his message into rural markets that have rarely seen so many presidential campaign ads.

And in Sacramento a week ago, Bloomberg offered California voters the chance to see something equally rare in the Golden State: retail presidential campaigning up close. At dawn, the billionaire worked his way through a crowd of curious voters at a downtown coffee shop and bakery, posing for selfies, urging voters — in signs, buttons and in his stump speech — to "vote early."

Crystal Strait, Bloomberg’s state political director, looking around the packed Sacramento event, said the campaign is running on all cylinders in California — dividing the state into seven regions for targeted mail and voter outreach, opening 20 offices and hiring 300 staffers. “He’s doing great, and we’re really feeling the momentum,’’ she said.

The former New York City mayor has picked up dozens of California endorsements in recent weeks, from big city mayors like London Breed of San Francisco, Sam Liccardo of San Jose and Antonio Villaraigosa, the former Los Angeles mayor and Assembly speaker, to rural Central Valley mayors like Kuldip Thusu of Dinuba and Eddie Neal of Lemoore.

But he has to play catch-up to Vermont Sen. Bernie Sanders, who has been the frontrunner in four recent major California state polls.

“The fact that we are leading in the biggest state in the country is a big deal — and we’ve been prioritizing it,’’ says San Francisco-based Ben Tulchin, the veteran Democratic pollster for Sanders’ national campaign. He says Sanders’ frontrunner status here is the direct result of consistent gains in California with three critical voter groups who may decide the state winner — Latinos, younger voters and the nearly 1 in 3 who have “no party preference” or are independents. “And our hard work is paying off.”

Tulchin says the Vermont senator has hit California more than any other candidate and in more diverse places — including the Central Valley and the fire-ravaged Northern California community of Paradise — and has opened 16 state offices to date.

That’s because Sanders views California as “the fifth primary,’’ after critical early contests of Iowa, New Hampshire, Nevada and South Carolina, Tulchin says. It’s a high priority not only because of the delegate numbers at stake, but because a win in the biggest and most diverse state in the union would “send a message” about Sanders’ electability against President Donald Trump going forward, he said.

In the last week, Sanders' team — which has opened 20 state offices and hired 90 paid staffers — has made an aggressive reach to appeal beyond the Democratic base. On Jan. 31, Sanders' key team leaders staged a press conference on the steps of the State Capitol in Sacramento in an attempt to woo the estimated 5.5 million nonpartisan voters eligible to cast ballots.

"That’s why we have been on the ground since Day 1 one educating Californians about the ins and outs of voting. We have an unprecedented opportunity to expand the Democratic electorate this cycle — and we aren’t going to waste it,” said Rafael Navar, Sanders' state campaign director.

Former South Bend, Ind., Mayor Pete Buttigieg, meanwhile, has outraised every other Democratic candidate in the state that is am ATM for the party — more than $9 million to date, according to Federal Election Commission data. He returns next week for four back-to-back fundraisers in the San Francisco Bay Area and Silicon Valley — ending the week with a town hall and rally on Valentine’s Day in Sacramento — events that political insiders say will be a hot ticket coming off his strong showing in Iowa.

Another Democratic billionaire, Tom Steyer, the only Californian still in the race following Sen. Kamala Harris’ exist last fall — insists that he’ll surprise the pundits here. His state campaign manager, Heather Hargreaves, says he has more than 400 staffers and nine offices on the ground — and the benefits of years of political outreach in his home state. As the founder of the Bay Area-based climate advocacy group NextGen Climate Action, Steyer has addressed tens of thousands of state voters in dozens of town halls he’s held on that issue alone, she says. “Climate is the issue that brought Tom into politics — and it’s an issue that resonates strongly with state voters, she says.

Former Vice President Biden’s California ties and work for the Obama administration have won him some plum endorsements, including Sen. Dianne Feinstein and her husband Richard Blum; uber-attorney and donor bundler Joe Cotchett; and two of California’s most prominent mayors, Los Angeles’ Eric Garcetti and Long Beach’s Robert Garcia.

But Biden has done no major retail events like the super-sized rallies that have been a hallmark of Sanders’ campaign here. He also failed to show up at two major Democratic party meetings here in California in the last months, including a Democratic state party convention where both Elizabeth Warren and Buttigieg not only roamed the venues buttonholing key delegates, but also appeared before California voters at enthusiastic rallies and campaign events.

A range of four to seven delegates are awarded in each of California’s 53 congressional districts, plus an additional 79 unpledged so-called superdelegates — many elected officials, including Gov. Gavin Newsom, as well as members of the DNC — putting the total at 494.

And “we are a massive state. You can’t traverse California in any significant way — even in one day,’’ says Mindy Romero, founder and director of the California Civic Engagement Project at the University of Southern California's Sol Price School of Public Policy.

Romero also notes that the ethnic diversity of California, a majority-minority state, also demands more from candidates hoping for an edge. “We have more voters that come from historically under-represented groups,’’ she says. Those include most significantly Latinos — who comprised 23 percent of the eligible voter turnout in 2016, more than double that of 2012.

And Asian Americans, she said, now make up nearly 19 percent, up 7 percent from 2012, both significant jumps. Their increasingly robust presence, she says, “can be a challenge in terms of messaging, in terms of translation of websites — and terms of finding a competent campaign staff and managers.’’

Complicating the matter: More than half of California now cast ballots by mail — with an estimated 45 percent expected to do so before the South Carolina primary on Feb. 29. Another new bump in the road for campaigns to consider: 2020’s primary marks the first California election where same-day registration kicks in.

Mitchell, vice president of political data and the founder of Redistricting Partners, a political strategy firm, argues there's no reason to expect a repeat of the recent Iowa meltdown in California. Golden State elections are not overseen by the party but by registrars in 58 different counties whose count will be backed up by paper ballots.

Still, he warns the sheer size of the state means results could likely be drawn out for days, perhaps weeks — which is why candidates like Bloomberg and Sanders are already "trying to front-load their efforts, and telling people to vote now."

No matter how the final results may shake out, Mitchell said, campaigns “know that what matters — for fundraising and momentum — is who is called the winner on election night … who technically gets a few more delegates.”