“There’s a three-out-of-four chance we are not the nominee,” Faiz Shakir, Sanders’s current campaign manager, says he tells the senator, “but that one-in-four chance is better than anyone else in the field.”

The senator from Vermont’s pitch is a mix of idealism and a shouting anger about the system, but at its heart is a hard-nosed math: He’s the only candidate with a sizable chunk of the electorate that won’t waver, no matter what, so a field that keeps growing and splitting support keeps making things easier.

He’s counting on winning Iowa and New Hampshire, where he was already surprisingly strong in 2016, and hoping that Cory Booker and Kamala Harris will split the black electorate in South Carolina and give him a path to slip through there, too. And then, Sanders aides believe, he’ll easily win enough delegates to put him into contention at the convention. They say they don’t need him to get more than 30 percent to make that happen.

So he’s eagerly gotten into fights, like one over the weekend with the Center for American Progress about a video produced by an affiliated website that speciously accused him of profiting off his 2016 run. And then he’s fundraised by citing the fights as evidence of resistance to the revolution he’s promising.

It is all wrapped in a tale Sanders tells of Democratic politics in which he is already the central figure—“only one name, and one name only,” as San Juan Mayor Carmen Yulín Cruz, a campaign co-chair, introduces him at rallies. Some of that is apparent: Medicare for all has become a litmus test for many progressives, as has free public-college tuition. Some of the tale, though, comes closer to solipsistic embellishment, like when Sanders says in his stump speech that “a funny thing happened over the last four years” and ticks through Democrats supporting investment in infrastructure, prioritizing climate change, and reforming the criminal-justice system—all of which were top focuses for Barack Obama.

Walking around a Sanders rally here on Sunday at Schenley Plaza, across the street from the University of Pittsburgh’s campus, it was hard to find a person who was not exactly the kind of voter the senator from Vermont believes will win him the nomination and make him the most electable in the general election: absolutely committed to him; very skeptical that there’s any other Democratic candidate to consider, or one who would be worth supporting in a race against Trump.

There was Tyler Litzinger, a Starbucks employee who came here on Sunday with three friends, who said that he is in the same place now as he was in 2016, when he supported Sanders but refused to vote in the general election after the senator lost in the primaries. Would he vote in the election if the 2020 nominee is anyone other than Sanders? “No,” he said. “I was one of those.” And as the one friend who said he’s still undecided between Sanders and Elizabeth Warren ribbed Litzinger and said, “We’re working on that,” the 25-year-old stood his ground. He doesn’t know if Sanders can get anything that he’s talking about done, Litzinger said, but Sanders winning is the only thing he’s interested in. As for the idea that that might help reelect Trump, he said, “I don’t follow that.”