“We won the House through the middle,” said Rep. Josh Gottheimer (D-N.J.), who co-leads the Problem Solvers Caucus. “Our party has to be open and recognize that. And if we don’t and insist that everyone takes a hard line view on everything, (a) I don’t think that’s going to attract votes in the next election, and (b) it puts our majority at risk.”

Sen. Joe Manchin III (D-W.Va.) said of his party’s shift to the left: “It makes it more difficult in more-rural areas like mine. Absolutely makes it more difficult.”

But many lawmakers — including 2020 presidential candidates — argue that a general push leftward is long overdue and reflects the broad popularity of many of their positions, from universal health coverage to taxing billionaires at higher rates.

“You can feel it now. In Congress, it has started to shift. It has started to shift. We’re not there yet. We’re not all the way there, but it has started to shift,” Sen. Elizabeth Warren (D-Mass.) said at a presidential campaign event Sunday night in Davenport, Iowa, when discussing her support for the Green New Deal. “We’ve got new energy in this. We’ve got new blood in this. We’ve got new ideas in this. No one is saying there’s a single silver bullet that’s going to fix the whole problem. What’s happening is people are coming up with lots of pieces.”