The W.F.P. is entirely pragmatic about the limitations of a third party in a two-party system. It runs primary challenges against centrist Democrats in places where more progressive candidates look viable, particularly in down-ballot races. But it’s careful not to act as a spoiler in general election fights, where it often works alongside Democrats. Cantor describes the W.F.P. as an “independent faction” of the Democratic Party; its model is more akin to the Tea Party than the Green Party.

“I want to be part of a left, but a left that has a very sober assessment of where we are today, so we can build this visionary future,” Mitchell said.

The W.F.P.’s endorsement is particularly sought after in New York, where the party was born and where it helped make Bill de Blasio mayor of New York City. Cynthia Nixon hopes to get its nod in her primary against Gov. Andrew Cuomo, and I suspect she will. Though Cuomo won the W.F.P. endorsement in 2014, many party activists believe he backtracked on his promises and feel betrayed. If the W.F.P. does throw its weight behind Nixon, it will be one of its highest profile challenges to an establishment Democrat and will elevate Nixon’s campaign considerably. “They know how to knock on doors and get out the vote, and they don’t give up,” Nixon told me via email.

Since 2010, the W.F.P. has expanded nationally and now has chapters or organizing committees in 19 states. In 2017, it endorsed more than 1,000 candidates for state and local office and helped elect people like Larry Krasner, the Philadelphia district attorney who is fighting mass incarceration, and Chokwe Lumumba, the mayor of Jackson, Miss., who aims to make his city “the most radical city on the planet.” Ryan Frankenberry, who founded the W.F.P.’s West Virginia affiliate last year, helped coordinate that state’s victorious teachers’ strike.

Building a party that can simultaneously encompass feminist actresses in Manhattan, black liberationists and white Appalachian strikers is no small thing. All over the world, right-wing populism is ascendant, and so far we have little evidence that multiracial left-wing populism can successfully challenge it. But one thing that Trump’s election taught us is that just because something has never happened doesn’t mean it can’t. “Can we merge these ideals with serious electoral heft?” Mitchell asked. People dreaming of a country that’s egalitarian, cosmopolitan and humane have no choice but to try.