Note: as I finish this piece Wednesday night, Graham Platner has just dropped his Maine Senate bid amid a sexual assault allegation. That's a real story, but it's a different one from the story below. Platner was never a DSA candidate, and he isn't leaving the race because Democratic voters rejected him — he's leaving because his endorsers fled overnight, not because of an ideological reckoning. What follows is about something else: a disciplined, organized movement that is winning clean primary votes against sitting incumbents, and doing it again and again.
In the spring of 2010, as Tea Party insurgents began knocking off Republican incumbents in primaries, the party establishment reached for a familiar reassurance. GOP leaders repeated the idea that the Republican party was a big tent, welcoming the movement as an infusion of energy that could be absorbed, and managed. Ohio Congressman John Boehner said “there really is no difference between what Republicans believe in and what the…
