Talk of popular control of the means of production is anathema to many older Democrats, even very liberal ones. It plays a lot better with the young; one recent survey shows that 61 percent of Democrats between 18 and 34 view socialism positively. The combination of the Great Recession, the rising cost of education, the unreliability of health insurance and the growing precariousness of the workplace has left young people with gnawing material insecurity. They have no memory of the widespread failure of Communism, but the failures of capitalism are all around them.

The D.S.A. alone neither claims nor deserves sole credit for the victories of candidates it endorses. Many groups came together behind Ocasio-Cortez, including the populist Brand New Congress and local chapters of the resistance group Indivisible. Nor was the D.S.A. the prime mover behind the Fiedler, Lee and Innamorato wins, though it helped in all of them.

Indeed, while there’s a lot of talk about an ideological civil war among Democrats, on the ground, boundaries seem more fluid. In Pennsylvania recently, I met with moderate suburban resistance activists who’d volunteered for Innamorato, thrilled to support a young woman who could help revitalize the Democratic Party.