Read: Joe Biden’s first-ever primary win is a big one

A split among the moderate candidates—Biden, former New York City Mayor Michael Bloomberg, Senator Amy Klobuchar, and former South Bend, Indiana, Mayor Pete Buttigieg—is also helping Sanders maintain his perch atop the field. Although Sanders is likely to cross the 15 percent threshold needed to collect delegates in virtually every contest on Tuesday, none of his opponents can say the same—at least according to the polls. Biden is strong in Virginia, North Carolina, and across the South, but weaker elsewhere. Klobuchar is battling to win her home state of Minnesota, while Senator Elizabeth Warren is looking to win in Massachusetts and rack up some delegates in California.

Then there is Bloomberg, the billionaire who has warned that Sanders cannot defeat President Donald Trump but whose candidacy may be helping the democratic socialist win the Democratic nomination. Bloomberg has shown strength in Texas and North Carolina, but his weak debate performances have stalled his rise in the polls. In a late bid to recapture support, the former mayor has purchased three minutes of national airtime on CBS and NBC tomorrow night to deliver a presidential-style address on the coronavirus.

Indeed, Sanders’s biggest threat is not any one of his opponents but a party establishment that remains nervous about his potential nomination. Within minutes of the polls closing in South Carolina tonight, pressure was building for some of the lagging candidates to drop out and rally behind Biden. “I’m hoping some of the candidates tomorrow get out,” former Virginia Governor Terry McAuliffe, a previous chairman of the Democratic National Committee, said on CNN as he endorsed the former vice president.

Sanders, however, would rather most of his rivals stay in for now—even if that means he takes a few losses on Super Tuesday. “A lot of states out there,” he said tonight. “That will not be the only defeat.”

In a sign of the increasing urgency of the calendar, Sanders devoted part of his speech to imploring young people to vote and to rebutting critiques of his electability in a race against Trump. Sanders needs a larger turnout among young voters to hold off his rivals and convince Democratic skeptics that he can win in the fall.

His double-digit defeat in South Carolina was a shellacking. If his landslide in Nevada suggested that Sanders had made deep inroads among the Latino community, the result in South Carolina is a reminder that he has a much tougher challenge in winning over African Americans, and particularly older voters.

More important, however, Sanders must hope that South Carolina is not the first sign of a broader national reconsideration of his candidacy. The answer to that question could be clear by Tuesday night.

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