“We’ll know soon enough if this trough is temporary,” I wrote back on June 19, “or if he’s done permanent damage to his re-election prospects among one of his most solid constituencies: white, working-class voters.”

Well, it’s late September, and polling in both states suggests that the Trump slump is real.

Back in mid-June, Biden’s average lead in Ohio, according to FiveThirtyEight aggregator, was 2.6 percent. Today, Trump looks better, but only slightly so. He trails Biden by an average of 1.1 percent. In Iowa, Trump’s narrow 0.6 percent lead over Biden in mid-June has barely budged. The latest FiveThirtyEight average puts it at 0.8 percent.

One big reason for Trump’s continued struggle in these states is his narrowing margins with white, working-class voters.