A few weeks ago, I met the liberal billionaire Tom Steyer at the W Boston hotel. Steyer has been playing a unique role in the midterm elections. He has been on a personal tour of the country, headlining rallies at which he lays out the case for impeaching Donald Trump (events at which he is regularly urged, from the crowd, to run for President). He has also pledged to spend thirty million dollars to help elect progressives, a sum that makes him the most significant Democratic donor in America. A San Francisco financier with a blue-blood Manhattan pedigree (Buckley, Exeter, Yale), Steyer has the tycoon’s habit of smiling broadly after he finishes speaking. As we spoke, Steyer kept returning to a point he makes often in public: that the Democratic Party is undergoing a profound generational change, and that he wanted to use his influence to help spur it along. I asked Steyer which politicians he believed represented this change, and he said, “Andrew Gillum.”

This wasn’t a name I’d expected. Gillum—the thirty-nine-year-old, outspokenly progressive, African-American mayor of Tallahassee, Florida—is running for governor this year, in a state that has been run by Republicans for nearly twenty years, and where Democrats usually nominate moderates. Gillum’s campaign platform calls for a steep corporate-tax increase to pay for a billion-dollar boost in public-education spending, a repeal of Florida’s Stand Your Ground law, Medicare for all, and a fifteen-dollar-an-hour minimum wage. The conventional wisdom, when Steyer and I spoke, was that Gillum’s chances in the Democratic primary were slim—the establishment favorite in the race was Gwen Graham, a former congresswoman whose father, Bob Graham, represented Florida in the U.S. Senate for eighteen years, and whose campaign emphasized environmental protection and the need for a more incremental approach to education and health care. Gillum was running third, fourth, or fifth in most primary polls, far behind Graham and the former mayor of Miami Beach, Philip Levine, a millionaire who was spending heavily on his own campaign, and who billed himself as a “radical centrist” and a problem solver. Gillum’s campaign, by contrast, was broke (his campaign aired its first television commercials only a few weeks before Tuesday’s primary), and was often mentioned in conjunction with an F.B.I. investigation into corruption in Tallahassee, which had orbited Gillum without directly implicating him.

Attendees at Gillum’s campaign stop in Miami Springs, Florida. Photograph by Scott McIntyre for The New Yorker

Yet in the past few weeks there has been a change. The local newspapers have been acknowledging that Gillum is “consistently the Democrat who can fire up crowds” as the Tampa Bay Times put it last week. Senator Bernie Sanders visited Orlando and Tampa last Friday to endorse Gillum and rally for him. In the public polls, Gillum has pulled close to Graham and Levine, in what is now clearly a three-way race, and in the private polls that have circulated among political operatives, samizdat-style, he is said to be closer still. Watching it from afar, I thought that Gillum’s campaign seemed a test, in inhospitable climes, of how far the progressive revolution might go. Could a new-model Democrat win in an old and conservative state like Florida?

Last Sunday, Gillum spoke at St. Ruth Missionary Baptist Church, in Dania Beach, Florida. I was in a pew near the back. Over six feet tall, with a shaved head and handsome, Gillum took the pulpit and told the congregation about his life. He was born poor, in Miami. His mother was a school-bus driver and his father was a construction laborer. He was the fifth of seven children, and the first to graduate from high school. While finishing college at Florida A. & M., he became the youngest city commissioner in the history of Tallahassee, and then, when he was thirty-five, he became its mayor. Gillum portrayed his own rise as proof that Florida had once been a more progressive place, and that the recent conservative regime has been a deviation. “We’ve got to reinfuse into our public education what used to exist there,” he said.

It was the conservatives, Gillum said, who had rejected the Obamacare Medicaid expansion that would have insured seven hundred thousand Floridians, and conservatives who had kept ex-felons, his brother among them, from voting. In Tallahassee, he had opened up most municipal jobs to those who had been in prison, and found that they were among the city’s hardest-working employees. “We can have that kind of state,” Gillum said. The congregation prayed over him, right arms extended.

Gillum at Notre Dame d’Haiti Catholic Church, in Miami. Photograph by Scott McIntyre for The New Yorker

The matter of how a poor young person might make it in a society arranged for the wealthy is one of Gillum’s main themes. At campaign events, he often introduced himself by saying he was “the only non-millionaire in the race.” At the outset, his campaign “couldn’t compete,” Gillum told me. “Look, what I’m facing here in Florida is decades of muscle memory around what our nominee is supposed to look like, sound like, where they are supposed to come from—I’m none of those things—even from progressives who may like me,” he said. “They also have muscle memory.”

But Gillum had also recognized that the big money in the Democratic Party—Steyer’s money, George Soros’s money—is now on the left, not the center. Last year, Gillum watched closely as Soros’s cash helped propel progressive candidates to victory in several local elections, including the Philadelphia District Attorney’s race. Gillum was familiar with Soros and his organization, the Open Society Foundation: a few years ago, he helped launch a national network for young progressive elected officials, and the Open Society Foundation was the group’s main donor. He had been in the financier’s New York apartment, addressed his board of directors, and, this spring, dined with him in San Francisco when the two men happened to be in town. Soros committed to back Gillum’s gubernatorial campaign. “If I’m remembering it correctly, it was, ‘We don’t know if you can win, but we would like what it could represent,’ ” Gillum said. “I interpreted it to mean that it would be significant to see a person of color taken seriously in a statewide race.”

Gillum managed to get a meeting with Steyer, too. “At the beginning, he told me he had a rule around trying to stay out of primaries,” Gillum told me. “As I talked to him about what I believed, I told him, straight up, ‘In your brand of politics, you are never going to have anyone come out of these primaries who shares that belief system if you don’t get involved.’ ” He needed money to beat money. On June 28th, Steyer’s organization, NextGen America, announced it would commit a million dollars to support Gillum’s campaign.

Gillum planned to spend the last week of his campaign on a bus tour of the state, beginning with a kickoff rally on Monday, at Kleman Plaza, in Tallahassee, just across from City Hall. The form of the event was familiar enough (a benediction, enthusiastic speeches, carefully plotted campaign signs, insufficient shade), but the content was a little unusual. Gillum’s wife, R. Jai, once an ally of his in Florida A. & M.’s student government, said from the podium that when the mayor had proposed, he had asked her to be his “life partner,” rather than his wife. Eleven ministers surrounded the Gillums and prayed for protection and success over them, clerical right hands placed on the Gillums’ bodies. “The son of second-class citizens,” one minister intoned. The usual program of patriotic songs was elided. In its place the crowd, racially diverse, sang all three verses of the unofficial black national anthem, “Lift Every Voice and Sing.”

Gillum at St. Ruth Baptist Church, in Dania Beach, Florida. Photograph by Scott McIntyre for The New Yorker

There’s a subtle generational seam running through the rising class of Democratic politicians. Those born in the late nineteen-sixties, such as Kirsten Gillibrand and Cory Booker, came up taking their cues from baby boomers and are now working to repurpose their politics to meet a more ideological party. Those born in the nineteen-seventies—Chris Murphy, Stacey Abrams, Kyrsten Sinema, Beto O’Rourke—have spent their careers closely watching the millennials, and explaining their evolving politics to the Party’s elders. Gillum, who was born in 1979, has been an especially keen observer. Gillum supported Hillary Clinton during the 2016 Presidential campaign—he spoke at the Democratic National Convention, and appeared on a long list of thirty-nine potential Vice-Presidential picks—and her campaign sent him to a historically black school in Columbia, South Carolina, before the primary there, on Clinton’s behalf. “Hillary and Bernie had events on the same day,” he recalled. He walked through campus, encountering black frat brothers and trying to entice them to the Clinton event. “They were, like, ‘Nah, we going to see Bernie.’ ” Looking back, Gillum said, he tended to think that the Sanders movement had not really been about its specific policy proposals—the students in South Carolina hadn’t been seeking out Bernie just because of free college tuition. “I’m not even certain that all of them believed it was possible.” Gillum said. “This generation—they’re not single-issue. They weren’t there for free college tuition. They wanted real change. Real reform. Something big.”