A Suffolk University/USA TODAY survey conducted last month of 638 voters who backed Sanders in primaries or caucuses this year found that 4% plan to vote for Trump – down from the 12% who voted for Trump over Clinton, according to a 2017 Cooperative Congressional Election study. The Suffolk poll has a margin of error of plus or minus 4 percentage points.

Brian Schaffner, a Tufts University political science professor who helped manage the 2017 study, expects to see fewer Sanders-Trump voters this time around.

Four years ago, Sanders-Trump voters included conservative Democrats already moving to the GOP and die-hards who wanted a populist to win, he said. It also included progressives who thought Trump would be defeated and couldn’t bear to vote for Clinton so casting a protest vote didn’t seem like a big deal, he said.

“Primary among most (2020) voters on the left is making sure Trump loses,” Schaffner said. “So most of Bernie’s supporters are going to support the Democratic nominee because the alternative is just something no one on that side of the aisle wants to live with for another four years.”