Clinton’s loss to Sanders in Michigan resembled a giant, mitten-shaped red flag. She won only 28 percent of self-described independents. She performed just as dismally among young people, winning 32 percent of voters under age 45. She was beaten in rural and exurban counties across the state, losing whites without a college degree by 15 percentage points. Even Clinton’s 40-point victory among black voters couldn’t make up for these deficits, because black turnout—as with Democratic turnout across the board—was so underwhelming. (There were 130,000 more votes cast in the GOP primary, a fact Democrats shrugged off at the time.)

Sanders’s team has long trumpeted his Michigan triumph as evidence of his ability to assemble a unique coalition and defeat the Democratic establishment. But a closer look at that contest, taken in the context of this year’s primary results, suggests that Sanders’s own weaknesses are about to be exposed. And that, in turn, means winning Michigan will be far more difficult this time around. Not only do party insiders expect Democratic turnout will spike among groups unfavorable to him—blacks and suburbanites, in particular—but he now faces an opponent in Joe Biden who comes into the state with a head of steam, who benefits from Democrats’ desire to coalesce behind an alternative to Trump, and who will compete for independents and working-class whites in a way Clinton never did.