On Tuesday night, 28-year-old Alexandria Ocasio-Cortez defeated the incumbent Democrat, Joe Crowley, in the primary race for New York’s 14th Congressional District. Ocasio-Cortez, whose election to the House in November is essentially a sure thing, was once an organizer for Bernie Sanders and has worked with the Democratic Socialists of America. Dave Weigel, a Washington Post national political correspondent, had been covering her campaign; he has also been reporting on and writing about the left’s political organizing and energy.

I spoke by phone with Weigel, who in addition to once covering politics for Slate is the author of The Show That Never Ends: The Rise and Fall of Prog Rock. During the course of our conversation, which has been edited and condensed for clarity, we discussed what is motivating the left’s activists, why Obama was able to appeal to the left and the center at once, and the dangers of reading too much into specific races.

Isaac Chotiner: Do you think that the race we saw last night is a one-off or that it tells us something about the future of the Democratic Party?

Dave Weigel: It’s a one-off only in that there are not many primaries left through the rest of the year where this is possible. I saw some chatter about how every Democrat is vulnerable, but literally while this was happening, Steny Hoyer—who is now probably 10 or 20 percent more likely to replace Nancy Pelosi—won his primary by like 70 points.