Progressive groups are getting more selective in targeting incumbents. Is it working?

In 2018, now-Reps. Alexandria Ocasio-Cortez and Ayanna Pressley shocked the political world by unseating 20-year incumbents in their Democratic primaries. And this year, the trend continued with progressives Marie Newman, Jamaal Bowman and Cori Bush winning their own upsets against long-serving congressmen.1

Thanks to an increasingly powerful progressive campaign apparatus, there’s no question that the left is now an established player in the Democratic Party. But is it strong enough to rival the political muscle of the party establishment?

To find out, FiveThirtyEight has once again tracked hundreds of endorsements in every Senate, House and governor primary completed so far this year (through Aug. 18).

And while the progressive upsets may have grabbed all the headlines, the numbers say the party establishment is still king of the hill. Of the 217 Democratic incumbents who ran in the primaries we analyzed, 214 won or advanced to the general election.3 Granted, that includes 19 incumbents — such as Reps. Ilhan Omar, Katie Porter, Rashida Tlaib and Ocasio-Cortez herself — who were supported by one or more of the six progressive endorsers we’re tracking. But in the 17 primaries where progressives (candidates endorsed by at least one of these six entities) went up against an incumbent, the progressive-backed candidate lost 14 times.

In primaries where there wasn’t an incumbent on the ballot, progressives did better: 22 wins4 (including Mondaire Jones in New York and Kara Eastman in Nebraska) to 10 losses (including Charles Booker in Kentucky). That’s a 69 percent win rate.