Democratic strategists believe the main reason why Biden, Schumer, and other rank-and-file leaders are acquiescing to the Squad is because they’re worried their own base won’t show up otherwise for next year’s midterm elections. They’re tracking the noise on social media as much as the data from their own internal polling. That concern is already cropping up in California, where low Democratic enthusiasm is making next month’s effort to recall Gov. Gavin Newsom uncomfortably close. It’s a factor in Virginia, where Republican engagement is a notch higher than Democrats’ intensity in a major bellwether contest in the post-Trump era, according to Democratic officials involved in the race.

Broadly speaking, it underscores a depressing dynamic in our modern politics: Narrow extremes are winning out against mainstream majorities. Just as Republicans are still held hostage to Trump’s destructive whims, Democrats are increasingly getting sucked into supporting out-of-the-mainstream policies embraced by the Squad—even when their own voters insist they want the party to move to the middle.

“The challenge our party has is that these elections have become base-mobilization contests. It all comes down to who turns out,” said one Democratic strategist. “Republicans have Donald Trump. We have … who?”