But the really ominous trend for Bernie Sanders is that his coalition is shrinking in the matchup against Joe Biden. Minnesota switched to a primary from a caucus system, and Biden won 38 percent to Bernie’s 29 percent; he also won non-college voters over Bernie 41 to 36. And crucially, he won white non-college graduates (fully 40 percent of Minnesota’s electorate) 44 to 32.

So it’s true that Amy Klobuchar’s and Pete Buttigieg’s endorsements are consolidating upwardly mobile suburban voters for Biden, particularly women. But the more sobering truth is that Bernie’s coalition is shrinking, and the great proletariat — America’s working families — are defecting to Joe Biden. The Minnesota and Oklahoma results suggest something about where states such as Michigan will go in the rest of the race; it won’t help Bernie if Biden softens him up across the Midwest.

Instead of being seen as an ideological candidate, Bernie is favored most by young college graduates who feel strained, and by voters in the Northwest, where there is a tradition of prairie socialism. The revolution of a multiracial working class that Bernie talks about swept across the country on Super Tuesday. It chose Joe Biden.