How United Are Democrats? A 96-0 Data Point Offers a Hint

Joe Biden has emerged from a contested Democratic primary with surprising party unity and without any serious threat on his left flank, according to New York Times/Siena College polls of the six battleground states likeliest to decide the presidency.

Over all, voters in the battleground states who said Bernie Sanders was their top choice for president said they backed Mr. Biden over President Trump, 87 percent to 4 percent. If there was a Bernie-or-Bust movement, it has either faded with the conclusion of the Democratic race, or it never existed in serious numbers in the battleground states.

Mr. Biden commands even more significant support from voters who supported Elizabeth Warren in the primary. The Democrats who said she was their top choice to be the Democratic nominee backed Mr. Biden over Mr. Trump by a staggering margin of 96 percent to 0 percent — even wider than Mr. Biden’s 96-1 lead among those who said he was their top choice in the Democratic primary.

No Warren supporter in the survey — which was conducted in June — allowed for the possibility that there was even “some chance” they would vote for Mr. Trump.

The unity of Democratic voters in the Times/Siena polls represents a marked change from four years ago, when a significant number of Sanders supporters never embraced Hillary Clinton’s candidacy. According to the Cooperative Congressional Election Study, she won just 74 percent of voters who backed Mr. Sanders in the 2016 primary, while 12 percent voted for Mr. Trump.

The findings, however, do not represent a change from last October, when Sanders and Warren supporters in the same six battleground states were asked whom they would vote for if the choice came down to Mr. Biden and Mr. Trump. It was 89-4 for Mr. Biden back then; it is 89-3 now.

Remarkably, the challenge Mr. Biden faces from the party’s left is difficult to distinguish from the challenge he faces from the center. Together, the supporters of Pete Buttigieg, Michael Bloomberg and Amy Klobuchar back Mr. Biden by 87-6. But these voters represent a smaller share of the Democratic electorate than the supporters of Ms. Warren and Mr. Sanders, and few would argue that Mr. Biden faces any serious challenge among moderate Democrats.

One reason Mr. Biden does not face the kind of rejection Mrs. Clinton saw is the changing composition of the Sanders vote. In 2016, Mr. Sanders won significant support from relatively conservative, white, rural voters. These voters were no socialists, and it’s an open question how many genuinely supported Mr. Sanders or merely voted in protest of Mrs. Clinton.

Either way, a share of Sanders supporters in the 2016 primary stuck with President Trump after backing him in the 2016 general election, and they did not return to Mr. Sanders in the primary four years later. Their departure from the Democratic primary electorate helps explain the significant decline in Mr. Sanders’s strength in white, rural and working-class areas, along with the relative unity of the remaining Democratic vote.

To be sure, the Democratic left is not necessarily excited to support Mr. Biden. Only 21 percent of Sanders voters and 40 percent of Warren supporters say they have a “very favorable” view of him, compared with the 77 percent of Biden backers who say they do. By 69-26, Sanders supporters say their vote is more a vote against Mr. Trump than a vote for Mr. Biden. Warren supporters also say it’s mainly a vote against the president, by a margin of 61 percent to 36 percent.

As the Biden team mulls a vice-presidential selection, one important consideration will be whether the relatively tepid level of enthusiasm he has generated poses a serious risk to his campaign. For now, opposition to Mr. Trump has largely overwhelmed whatever reservations these voters have about Mr. Biden, especially among Ms. Warren’s supporters.

Not only are Warren supporters likelier to support Mr. Biden than his supporters in the primary, but Warren voters are also likelier to say they’re “almost certain to vote” in November. They’re nearly as enthusiastic about voting as well: 75 percent of Warren supporters say they’re “very enthusiastic,” compared with 80 percent of Mr. Biden’s supporters.

The Sanders supporters show more disappointment, although at a modest level. Only 47 percent said they were “very enthusiastic,” and 64 percent said they were “almost certain to vote.” The latter tally is somewhat smaller than the 70 percent of Biden supporters and 72 percent of Warren supporters who registered the highest level of intention to vote. But it’s fairly healthy given that younger voters tended to support Mr. Sanders and are generally less likely to vote.

Even so, respondents who said they supported Mr. Biden in the general election were just as likely as President Trump’s supporters to say they were “very enthusiastic” or “almost certain to vote.”