Liberal Democrats Ruled the Debates. Will Moderates Regain Their Voices?

Representative Cedric Richmond of Louisiana, a co-chairman of Mr. Biden’s campaign, said Democrats needed to work toward the interconnected goals of winning both the presidency and the Senate. Those tasks will be more difficult, he said, if the 2020 candidates have to support and defend controversial policy proposals.

“I believe there’s a way to energize the base, and at the same time not lie to the base and promise a whole bunch of things we know we can’t get done,” he said.

Dan Sena, a Democratic strategist who led the party’s campaign to take control of the House last year, warned that Democrats were at risk of moving too far left to assure a wide range of voters that they supported broadly popular positions like securing the border and preserving popular provisions of the Affordable Care Act.

“If you don’t lay the groundwork — the purpose for your candidacy and the larger picture on health care and immigration — you will have a harder time getting the electorate to listen,” said Mr. Sena, who is advising Mr. Bennet. “The further left one goes, the further away one gets from a larger pool of swingable general election voters.”

But such sentiments only evoke eye-rolling among other Democratic strategists, who believe that such up-for-grabs voters are disappearing in this tribal era of politics.

“You are competing for a smaller and smaller band of undecided voters,” said Anne Caprara, who ran J.B. Pritzker’s campaign for governor of Illinois last year.

Ms. Caprara argued that Republican scare tactics were inevitable no matter the Democratic policies — “Nancy Pelosi is coming for your children!” as she put it — and that Mr. Trump’s incendiary language and divisive politics had created “a wider berth” for Democrats to pursue progressive policies.

“The horrors of Trump’s immigration policies have made it easier to have a bigger conversation about embracing immigrants,” she said, also pointing to abortion rights, where Republican efforts to ban the procedure outright have opened the eyes of some otherwise moderate voters that Roe v. Wade “is in real jeopardy,” adding that, “The landscape has changed. This is not 1995.”