Can Bernie Sanders and Joe Biden Unite the Democratic Party?

The news media tends to focus on the Bernie or Bust types, supporters of Mr. Sanders who have vowed not to vote for any other Democrat in November; last weekend, the well-known comedian and podcast host Joe Rogan, who had endorsed Mr. Sanders in January, said that he would probably support Mr. Trump over Mr. Biden. “I can’t vote for that guy,” Mr. Rogan said of Mr. Biden on his podcast.

Not surprisingly, backers of Mr. Biden’s tend to espouse a more hopeful — or wishful — view that 2020 will be different. There are, in fact, many fewer Bernie-to-Trump voters than it may seem. “He’s got some loud ones, there’s no question,” Mr. Reid said of Sanders supporters. “But that’s a small group of people.”

Mr. Biden brings more good will to a potential partnership with Mr. Sanders than Mrs. Clinton ever did, Mr. Reid said. There also appears to be far less personal animosity between Mr. Sanders and Mr. Biden than between he and Mrs. Clinton.

“There is a completely different dynamic now than in 2016,” said Terry McAuliffe, the former governor of Virginia and onetime Democratic National Committee chairman who has endorsed Mr. Biden. Four years ago, Mr. McAuliffe said, he believed that Mr. Sanders knew he would run again if he did not get the nomination, so it was in his interest to keep his supporters engaged and aligned with him. “This time, running again is not in play for either Bernie or Biden, so everyone has incentive to work together,” he said.

The single biggest difference between 2016 and 2020 is that the prospect of Mr. Trump is no longer hypothetical, Mr. McAuliffe said.

“I think there were a lot of folks who didn’t want to vote for Hillary, or who thought that Trump was a business guy, let’s give it a try,” Mr. McAuliffe said.

“Now he has this horrible record to stand on,” he continued. “There’s nothing more unifying for Democrats than that alone.”