The Sanders team signalled that it was shifting focus to the midwest when it canceled a planned rally in Mississippi. Instead, the candidate headed to Michigan for an event on Friday night.

The move was a tacit acceptance that Biden now has a stranglehold on southern states, propelled by his popularity among black voters. It was also recognition of the high stakes of the primary in Michigan, with its rich pickings of 125 delegates out of the 1,991 needed to win the nomination.

Sanders sees Michigan as a chance to regain his stride after the knocks of Super Tuesday, having beaten Hillary Clinton there in 2016. He hopes that his focus on policies appealing to working-class Americans, such as a federal $15 minimum wage, will play well not only in that state but across the rust belt in Illinois and Ohio, which hold their primaries on 17 March.

“Michigan is an enormously important state,” Sanders said in a post-Super Tuesday press briefing in his home town of Burlington, Vermont. “The people of Michigan were devastated by trade agreements which I vigorously opposed and Joe Biden supported.”