Diamondstone called Sanders a “quisling” after endorsing Walter Mondale for president in 1984.

While Sanders has never been associated with such alleged shenanigans, he’s made a number of alliances and compromises that have drawn harsh denunciations from a more demanding faction on his left. Diamondstone called him a “quisling” after Sanders endorsed Walter Mondale for president in 1984. Parenti split with him over his support for armed intervention in the former Yugoslavia. And some members of his own government joined the protest at the GE factory. He has called repeatedly over the years for a third party, only to run for president as a Democrat and remain somewhat aloof from the Vermont Progressive Party.

But precisely because he’s not a rigorous intellectual or theorist, these evolutions and changes do not wear on his soul. He is, in other words, a politician, as Guma observed in that Burlington coffee shop all those years ago. And he wins.

The Greens, by contrast, evaporated as an electoral force in Burlington. After the collapse of the Greens, Bookchin’s political world got smaller and smaller. He was exhausted and alienated by his long-running and harsh dispute with radical “deep ecologists” in the U.S. environmental movement. The Green Party would evolve into a more conventional political party, while few anarchists adopted his political ideas. Wheelchair-bound in his later years (he died in 2006), Bookchin told the longtime Burlington political activist and former city attorney Gene Bergman, “I don’t have the energy to fight anymore.”

Biehl herself, while studiously tending to Bookchin’s legacy, described Sanders as a “superb” senator, who was “fighting tenaciously on behalf of the downtrodden.”

That is not to say that Bookchin’s political vision died somewhere in Burlington in the 1990s. While Sanders was serving in Congress, Bookchin’s work made its way to the Turkish jail cell of Kurdistan Workers’ Party leader Abdullah Öcalan, eventually leading the party to explicitly model itself on Bookchin’s ideas. Öcalan, previously a Marxist-Leninist militant, now describes his political beliefs as “Democratic Confederalism.” Today, the area of northern Syria under Kurdish control is governed along Democratic Confederalist lines, based on Öcalan’s interpretation of Bookchin. The region is also home to some of the fiercest and most loyal fighters against ISIS in Syria. If Sanders were to win the presidency in 2020, some 40 years after Bookchin’s anarchists helped him win the Burlington mayoralty, it would be a great twist of fate that their two “people’s republics” would be allies once again.

When Sanders burst onto the national stage in 2015, mainstream liberals didn’t quite know what to do with him. Hillary Clinton and her supporters could not simply portray him as a radical ideologue with foolhardy plans that could never be implemented—as Sanders likes to point out, many of his policy proposals poll quite well. So he wasn’t just hopelessly left-wing, Clinton and her allies contended, he also was hopelessly out of date with how Democrats talk and think about race and gender. He was, at best, tone-deaf to the specific grievances and issues faced by people of color and women and, at worst, actively hostile to any form of politics that wasn’t his type of class-based, “bread and butter” progressivism.

Clinton assailed Sanders as a “single issue” candidate, while she was “the only candidate who’ll take on every barrier to progress.” Or as she put it in a remark that best sums up how the longtime triangulator positioned herself on both the right and left of Sanders: “If we broke up the big banks tomorrow ... would that end racism?” The political figure most associated with Democratic moderation in pursuit of electoral success (besides her husband) was now both the liberal establishment and Bookchin, with Sanders caught in the middle, hammering away at inequality and universal health care. For the first time in nearly 30 years, he lost.

But so did Clinton eventually, and she lost in the exact places where Sanders’s persistently populist message might resonate the most: the Rust Belt. The not-so-unreasonable supposition that Sanders could have beaten Donald Trump, along with a new solid base of activist support, made him an instant frontrunner for the Democratic nomination in 2020.

His subsequent campaign can be seen as one long correction to this critique that he wasn’t all the way there on race and gender, while not giving any ground on the policy questions. His staff is more diverse and he’s been prompted to talk about his personal history, which includes his time in college as a civil rights activist in Chicago. He’s still polling a distant second to Joe Biden—who has been leading in polls among older and African American voters—and has been splitting the support of ideological left-wing Democrats with Elizabeth Warren, who has exceeded him in putting out detailed, progressive policy proposals.

But no matter what happens in 2020, Sanders has distinguished himself from past leftists who tried to make their mark on national politics. He’s no Norman Thomas or Gus Hall or Barry Commoner. He’s not a beautiful loser, a protest candidate, or a spoiler. Still, he’s not part of any larger movement or tendency either. His distance from both the Democratic Party and any sectarian left organizations has given him the flexibility to contest and win elections for four decades. But it also means that his socialism is his alone. At the moment, the only way to establish what socialism can mean in the twenty-first century is for Sanders to win.