But those moves remain the exception within the party. Some Democrats say they erred in 2016 by antagonizing Sanders and his supporters, and they are loath to risk doing so again. Others warn that treating Sanders too gently, however, could repeat the Republicans’ experience of 2016, when they underestimated Donald Trump until it was too late to stop him.

Either way, the anxiety is palpable.

“If Bernie is on the ticket as the nominee, I have no chance whatsoever,” said one Democratic House candidate in a swing district, speaking on the condition of anonymity for fear of antagonizing Sanders supporters. “And if you wrote that, it would blow me up in the primary.”

The candidate added, “Bernie has a real following. But it’s a minority, and he turns off a whole lot of people.”