Trump’s weakened standing reflects the region’s continuing struggles. Michigan is a case in point. Last fall, General Motors Co., announced plans to end production in two southeastern Michigan auto plants. Data from the U.S. Commerce Department’s Bureau of Economic Analysis shows that personal income growth in Michigan during Trump’s presidency is among the lowest of any state. And in recent weeks, Trump started a Twitter attack on the United Auto Workers, blaming union leaders for GM’s decision to idle a plant in Lordstown, Ohio.

“The optimism and excitement you heard from workers two years ago is mostly gone,” said Mark Gaffney, former Michigan president of the AFL-CIO. “A lot of those people haven’t abandoned him. What you hear now is, ‘He’s being picked on by the liberal media.’ But his support is diminished.”

One flashing warning for Trump is that voters who backed President Barack Obama in 2012 and went for Trump in 2016 have begun to peel away. In a March 21 poll, Optimus, a Republican data-research firm conducting an ongoing study of Michigan, Wisconsin and Pennsylvania, found that Obama-to-Trump voters were willing to defect to an array of the Democrats running for the party’s presidential nomination.