As the battle for the Democratic nomination narrows to what could become an extended standoff between Bernie Sanders and Joe Biden, California looms as the biggest delegate prize on the Super Tuesday calendar. But if the race is close and with millions of ballots to count, it could be days, if not weeks, before we know who won the most delegates.

A trove of 1,344 delegates will be awarded in Tuesday’s contests — about a third of all the pledged delegates available in the nominating contest — giving the top voter-getters a major boost toward the 1,991 delegates needed to win the Democratic nomination.

With his deep organizing roots here, Sanders appeared to be best positioned to capture a sizable portion of California’s 415 delegates, the largest number among the 14 states, plus American Samoa, that will vote Tuesday.

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The Vermont senator has been posting double-digit leads in California. But most of the state’s polling was done before the former vice president’s big win in South Carolina this past weekend, and before former South Bend, Indiana, Mayor Pete Buttigieg and Minnesota Sen. Amy Klobuchar dropped out of the race and endorsed Biden.

Sanders led the latest CBS News/YouGov poll of the Golden State with 31% of likely voters, followed by Biden at 19% and Massachusetts Sen. Elizabeth Warren with 18%. Former New York Mayor Michael Bloomberg, after spending more than $55 million on television ads here, was at 12%.

“Bernie Sanders has run a five-year campaign in California … He had a leg up here from the get-go,” said longtime California strategist Bill Carrick, noting Sanders’ intense campaign in the Golden State before the 2016 June primary, which he lost to Hillary Clinton.

But because of California’s size, complexity and the expense of advertising here, the presidential campaigns have always viewed California as a momentum state. Carrick said there’s no question the South Carolina results will have a “catalytic effect” on the race here.

Here’s what to watch for in California on Super Tuesday:

Delayed results

When waiting impatiently for California’s results this week, it’s important to remember the sheer volume of ballots that must be counted and verified, with the added twist that California voters can postmark and mail in their ballots on Election Day.

In an effort to expand participation in a state with 20.5 million registered voters, some 16 million ballots were sent out to voters across the state this year, and officials tried to encourage early voting by opening “vote centers” throughout the state 10 days before the election (adding more centers four days before the election).

As of Monday, 22%, or 3.6 million, of the early vote ballots had been returned, according to the firm Political Data Inc.. But because voters can postmark their ballots on Tuesday, county registrars must literally wait for up to three days, March 6, for the letter carriers to deliver them under state law.

“There’s so much misinformation about this and I saw it firsthand in my own election,” Democratic Rep. Katie Porter, who defeated Republican incumbent Mimi Walters in California’s 45th congressional district in 2018. “They work very, very hard, our postal employees, to get those ballots to the registrar as quickly as possible. But then there is a very careful process of opening those mail ballots, making sure that it is not a mail ballot that corresponds to somebody who also voted in person. So that is all verified individually with multiple people making those kinds of checks.”

Porter noted that state officials must also verify the signature on the ballot against the voter’s signature that is on file.

“There’s an incredibly careful process and, as we saw in my own election in 2018, it just takes time to do that,” Porter said. In one notable example, the race for California’s 21st District in the US House wasn’t called until former Republican Rep. David Valadao conceded on December 6, 2018 — a full month after Election Day.

Potential miscues in early results

Polls don’t close until 11 p.m. ET in California and the first batch of early votes counted is generally posted within an hour of polls closing. But it’s important not to read too much into that first batch, because the numbers typically aren’t representative of where the results will end up.

Paul Mitchell, vice president of the nonpartisan voter data firm known Political Data Inc., explains that the group of voters who mail in their ballots the earliest tend to be older and less diverse than the California electorate. Younger voters and voters of color are more likely to turn out on Election Day.

That first batch is likely to include “older, more conservative voters who vote by mail regularly, and potentially a bunch of people who knew they were going to vote for Sanders,” Mitchell said. “So we might see a really weird result there.”

California began mailing out ballots on February 3 — the day of the Iowa caucuses — and some of the earliest of the ballots were mailed back before Sanders’ victory in Nevada and Biden’s victory in South Carolina. So those first results will likely not reflect the ebb and flow of the presidential race in recent days.

Because of Democratic indecision this year, Mitchell noted that a sizable portion of high-propensity, high-information voters appeared to be holding on to their ballots, presumably because they wanted to see what happened in South Carolina or if some of the lower-polling candidates dropped out.

It’s hard to measure voter enthusiasm this year simply by the number of ballots returned because of that indecision — and also because a much larger share of ballots were sent out this year, 16 million, compared to 2016, when 10 million were mailed. There are also 2.5 million more voters in California now than there were in 2016.

Changes for voters

The state tried to expand voter participation through its California Voter’s Choice Act in 2016. The changes under that law meant that many more voters received mail-in ballots this year, but it also meant that independent voters, known as “no party preference” voters, had to request a party ballot that included presidential candidates if they wanted to vote in that contest.

That change has surprised no party preference voters who waited to open their ballots and found they didn’t have a way to vote in the Democratic contest.

Those voters can still participate if they bring their mail ballots to a vote center in their county and request a “crossover” ballot that lists the Democratic, Libertarian or American Independent Party presidential candidates. The Sanders campaign has done extensive outreach to flag that change to independent voters who are supporting him.

California also expanded same day voter registration, which is now available at every polling place, county election office or vote center. Those voters will be asked to fill out a voter registration form, and their ballots will be counted after the county elections office has verified their voter registration.

All of that could amount to more ballots to count after Tuesday. But state officials signaled early this year that they are in no rush. Secretary of State Alex Padilla pre-emptively put out a statement noting that county election officials have 30 days to count every valid ballot and conduct a post-election audit.

Padilla added that the California prioritizes “the right to vote and election security over rushing the vote count.”

“In California, we’d rather get it right than get it fast,” he said.