Biden Thinks Trump Is the Problem, Not All Republicans. Other Democrats Disagree.

Some Democrats say the idea of trying to predict electability and casting Mr. Trump as an “aberration” was tried by Mrs. Clinton in 2016 — and it failed.

“I feel like the party went through this and the 2016 election showed that Trumpism isn’t just Donald Trump — it’s the entire Republican Congress, too,” said Rebecca Katz, a progressive Democratic strategist unaligned in the 2020 contest. “Until there is someone in the Republican Party who can stand up to Trump, then none of them are better than Trump.”

Republicans aligned with Mr. Trump say that, whatever the president’s failings, he has overseen a growing economy, the appointment of a vast array of conservative judges and a huge tax cut. They note that they offer dissent when they disagree with his policies; Mr. Trump recently suffered setbacks on his desired nominations to the Federal Reserve, for example, because of Republican opposition.

In a 21-candidate Democratic field, Mr. Biden, of course, is not the only candidate running as a potential healer. Senator Cory Booker has described seeking “to channel our common pain into common purpose.” Senator Amy Klobuchar talks up her bipartisan credentials. And Senator Michael Bennet entered the race this past week making the case for moderation as a “pragmatic idealist.”

But Mr. Biden is, by far, the most prominent.

At an Iowa City brewery, as Anne Spencer considered whether she would support the former vice president, she wondered what ever happened to all of Mr. Trump’s Republican critics in 2016. “The ones who spoke out against him are now with him,” she said. “It just makes one question our system.”

“We hope,” she added of Mr. Trump, “he’s an aberration.”

A few minutes later, Mr. Biden was onstage plugging the need to work together. “We have to unify this country,” he said. “It’s not just about — the other side is not my enemy, it’s my opposition. And folks, we’ve got to take it on, we’ve got to take it on in a real way.”