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.