Polls make clear that most college-educated voters share many of Comey’s doubts about Trump. Three national surveys released this week (ABC/Washington Post, NBC/Wall Street Journal, and NPR/PBS NewsHour/Marist) each put Trump’s approval rating among whites with at least a four-year college degree at 41 percent or less.

That’s far below what a Republican president would typically draw, and it is creating a powerful undertow for GOP candidates. Each poll showed that about half of college-educated white voters now say they intend to support Democrats in the congressional elections, while only about two-fifths intend to support Republicans. That’s a major shift from both the 2010 and 2014 midterms, when exit polls showed nearly three-fifths of college-educated whites preferred Republicans in House races. Two state-level polls reinforce the movement evident in these national surveys: This week’s Muhlenberg College survey showed a nine-point lead for Democrats among college-educated whites in Pennsylvania, and a new Monmouth University poll showed Democrats running even with those voters in New Jersey.

These attitudes are virtually certain to power Democratic gains in suburban districts, such as those in and around New York and New Jersey, Philadelphia, Chicago, Minneapolis, Northern Virginia, and Los Angeles. They could even have an effect in more traditionally Republican-leaning territory near Houston, Dallas, Atlanta, and Omaha.

But it remains a close call on whether Democrats can flip enough of those upscale, metro districts to regain the House majority. The party would have a much easier path if it could also capture at least some Republican-held seats that are more blue-collar and non-urban, in places like upstate New York, downstate Illinois, and Iowa.

Winning working-class voters is even more essential for Democrats in the Senate, where the party is defending 10 seats in states that Trump carried in 2016. Most of them are preponderantly white and heavily blue-collar, including West Virginia, North Dakota, Montana, Missouri, and Indiana.

It isn’t clear that the case against Trump’s values is a winning argument in those places. All three national polls released this week placed Trump’s approval rating among whites without a college degree below his commanding two-thirds in 2016. But he remained positive with those voters overall, and in each survey they preferred Republicans over Democrats for Congress by at least 13 percentage points. That’s despite last week’s nonstop news about Comey’s new book; the continued sparring between Trump and Daniels, the adult film star; and the FBI’s raid on Cohen, the president’s longtime “fixer.”

Trump has forged a powerful connection with many working-class whites by expressing their anxiety about cultural, demographic, and economic change. If there’s an opening for Democrats among these Americans, it’s through discrediting Trump’s argument that he’s championing working-class interests against powerful elites. For Democrats, the key is building a case that Trump, for all his posturing as a working-class hero, has increased economic insecurity for average families. They could do so by highlighting his attempts to repeal the Affordable Care Act, along with his support for a tax plan that mostly benefited the wealthy and corporations and will eventually increase pressure to cut Social Security and Medicare.