In 2016, exit polls showed that Hillary Clinton actually did better among non-college white voters in Ohio than she did nationally, reflective of a longstanding blue-collar Democratic tradition in parts of the state. Among white voters with college degrees, meanwhile, the opposite was true: She underperformed especially badly in Ohio, where staunch white-collar conservatism is a long-held custom.

The result is that Mr. Trump did almost as well among white people with a degree in Ohio — who deeply distrusted Mrs. Clinton — as he did among those without a college education.

But this has all changed. Averaging together the recent Fox and Quinnipiac polls, Mr. Trump was running 12 points behind his 2016 totals among white voters with degrees.

As a result, while exit polls four years ago showed Mr. Trump winning the suburbs in Ohio by 20 points — leagues better than his support in suburbs elsewhere in the country — the Fox poll last week put him 10 points behind Mr. Biden in the state’s suburbs.