WASHINGTON — The Democratic contest is rapidly becoming a two-person race between establishment-friendly moderate Joe Biden and progressive populist Bernie Sanders. Super Tuesday will determine which one has the edge — and whether any wild cards remain in the hunt.

It's the biggest day on the primary calendar, with one-third of Democratic delegates up for grabs in 14 states — Alabama, Arkansas, California, Colorado, Maine, Massachusetts, Minnesota, North Carolina, Oklahoma, Tennessee, Texas, Utah, Virginia and Vermont — as well as the territory of American Samoa and the votes of those living abroad.

Here are seven things to watch on a critical day of voting as the race narrows to four major candidates — Biden, Sanders, Elizabeth Warren and Mike Bloomberg.

1. Can Biden capitalize?

The Democratic establishment is in "stop Sanders" mode, and Biden is their man. The endorsements have been pouring in for the former vice president after his blowout victory in South Carolina three days ago. Former Senate Majority Leader Harry Reid, D-Nev., and Sen. Tammy Duckworth, D-Ill., were among those who added their names to the list Monday.

Saturday's vote rejuvenated the former vice president's campaign and led two moderate rivals — Pete Buttigieg and Amy Klobuchar — to drop out and endorse him. Now it's up to Biden to take advantage. The rapid consolidation of party elites could nudge Democrats toward Biden if they're hunting for an alternative to Sanders.

2. Where do Buttigieg supporters go?

Before he quit, polls found Buttigieg winning the support of about 10 percent of Democrats nationwide. That's a hefty chunk of votes in a primary campaign that could go down to the wire. Whom will they support now?

Buttigieg wants his voters to switch to Biden — he praised him Monday as the candidate who would "bring dignity back to the White House" — but they may have other ideas. Ahead of his endorsement, the most recent numbers from Morning Consult, which tracks "second choice" preferences for candidates, found that among Buttigieg voters, 21 percent would go to Sanders, 19 percent each to Biden and Warren and 17 percent to Bloomberg.

3. Demographics matter more than 'momentum'

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"Momentum" hasn't defined the Democratic contest so far. The Iowa victory didn't turn Buttigieg into a force, the New Hampshire "Klomentum" didn't last, going 0-for-3 didn't sink Biden, and two decisive victories didn't make Sanders unstoppable.

The story of the primary season so far has been demographics: Latinos and young people have embraced Sanders, black voters have overwhelmingly supported Biden, and white voters are all over the map.

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That bodes well for Sanders in California and Texas, the two most delegate-rich states on Tuesday. The senator from Vermont won Latinos by more than 30 points in Nevada, according to NBC News entrance polls.

And it's good news for Biden in Alabama, Arkansas and North Carolina. He won 61 percent of African American voters in South Carolina. History is on Biden's side: The candidate who has carried black voters nationally has won the Democratic nomination in every contested primary since 1992.

4. Is Mike Bloomberg the real deal?

The billionaire entrepreneur skipped the early states and put all his chips on Super Tuesday. He has spent more than half a billion dollars on TV, radio and digital advertising. He has built a powerhouse of an operation in states like North Carolina, and he was campaigning in Utah, Oklahoma and elsewhere while his rivals were barnstorming the first four contests.

This is his moment to show he's the real deal. Some moderate Democrats fear that he's playing spoiler for Biden, scooping up middle-of-the-road voters and helping Sanders, who Bloomberg has insisted would devastate the party up and down the ballot if he were the nominee. Bloomberg is already facing pressure from moderates to drop out and help Biden. If he doesn't put big victories on the board Tuesday, those calls will only intensify.

5. Can Warren's campaign be resuscitated?

Warren became the last major woman candidate in a majority-female party one day before Super Tuesday. Will it matter? Or is it too late for the senator from Massachusetts? After finishing third, fourth, fourth and fifth in the early states, her campaign has all but conceded that she won't clinch the nomination before the convention — but it argued that nobody will.

On the heels of having raised $29 million last month, campaign manager Roger Lau vowed in a memo that Warren would keep fighting, envisioning a long slog of a delegate haul that ends in a "final play" for nomination at the convention in Milwaukee in July.

It's one thing for a struggling campaign to keep all avenues open to give supporters hope, but asking for the nomination while trailing in pledged delegates is another matter. No major party convention has gone beyond the first ballot since 1952.

Warren's home state votes Tuesday, and defeat there could signal an end to her campaign. Recent polls show Sanders narrowly leading Warren, and he paid a visit to Boston for a rally Saturday that drew more than 10,000 people. He didn't mention Warren.

6. The crucial 15 percent threshold

Winning a state is a trophy, but delegates are the real prize — a candidate needs to hit 1,991 to capture the nomination. A minimum threshold of 15 percent is required statewide to win any delegates, and the number awarded is calculated based on results in congressional districts.

There are two titans heading into Super Tuesday: Sanders, with 60 delegates, followed by Biden, with 53. The next active candidate, Warren, has just eight.

7. Will the field narrow further?

Super Tuesday will determine whether there's a clear front-runner or whether the race will be a drawn-out fight. It will also reveal whether Bloomberg or Warren will hang on as wild cards — or spoilers for their ideological counterparts.

Morning Consult polling suggests that Bloomberg voters' top second choice is Biden and that Warren supporters' top second choice is Sanders. As Biden racked up endorsements Monday, Warren also faced pressure to step aside from Sanders supporters, who lit up Twitter with the hashtag #WarrenEndorseBernie.