It certainly feels like Bernie Sanders is winning. Judging from his soaring rhetoric, celebrity endorsements, and huge rallies, the Vermont senator lately seems like he could ride his political revolution all the way to the Democratic nomination without breaking a sweat. Of the last eight primary contests, Sanders has won seven. On Sunday, more than 28,000 people turned up to hear him speak in Brooklyn, and on Monday, a new national poll showed him virtually tied with Hillary Clinton, 48 to 50 percent—a 4-point increase that puts him within the margin of error.

And yet, Sanders is well on his way to a resounding defeat. On Tuesday, he is expected to lose New York, where state law prevents independents, some of his strongest supporters, from voting in the Democratic primary. (“Nothing much I can do. It’s bad New York state election law,” he groused on Monday.) A series of recent polls indicates that Clinton, despite a spate of bad press, is still solidly on track to secure the presidential nomination based on her commanding delegate lead.

To be fair, Sanders has beaten the odds before. In Iowa, he overcame a double-digit deficit to virtually tie with Clinton, and in Michigan, he shocked pundits by leapfrogging her 20-point lead to win the entire state. But even if he pulls off similar victories in every single state left in the race, Sanders would still trail Clinton among delegates, who are awarded proportionally, and super-delegates—party leaders who can side with either candidate, irrespective of their state’s vote, and who have largely sided with Clinton. “Bernie Sanders would have to win landslide after landslide starting in New York to change that math,” David Axelrod, President Obama’s former campaign strategist, said on CBS’s Face the Nation Sunday. “He’s run a splendid campaign . . . but at this point, it just looks like time is running out.”

At the moment, Sanders lags Clinton by double digits in all the major upcoming states, New York included, making those landslides highly unlikely. While pointing to the Michigan model as their pathway to victory, the Sanders campaign has quietly begun dialing back expectations for Tuesday. “Here’s the truth: we don’t have to win New York on Tuesday, but we have to pick up a lot of delegates,” Sanders campaign manager Jeff Weaver said in an e-mail Sunday pointing to polling showing the candidate within 6 points of Clinton. “This poll shows that if we keep fighting, we may actually have a chance to do both.”

The other major reality check facing the Sanders campaign is his lack of super-delegates, the majority of whom have backed Clinton, extending her delegate lead from 244 to 682. Even if Sanders manages to win a series of landslide victories—rather than a more likely scenario in which he merely prevents her campaign from surging ahead—he’ll be hard-pressed to swing those uncommitted delegates over to his side. Much like Ted Cruz with Donald Trump, Sanders’s only realistic shot at fighting on to the general election involves blocking Clinton from securing the number of delegates needed to clinch the nomination (2,382, for the Democrats) and then persuading them to vote for him at a contested convention.

Should it get to that point, Sanders may have a viable argument that he is the more electable candidate. Nationwide, he’s virtually tied with Clinton in the polls, and several (albeit unreliable) surveys show him soundly beating the presumptive G.O.P. nominee, Trump, in a general-election matchup. But if Sanders stays too long in the primary and loses, his moral victory will be a pyrrhic one. The surge of Democratic passions surrounding the self-styled socialist, fueled by rising anger against wealthy interests, has exacerbated a widening rift in the party, decreasing Clinton’s favorability rating and damaging her reputation before the general election even begins. One in four Sanders voters say they won’t vote for Clinton if she is the nominee. Soon, that conviction may be tested: with less than a day to go before the New York primary, voters will decide whether the dream of Sanders’s political revolution will live another day, or die.