Over that history, this has been a story largely about class and race. But what’s happening in 2016 is still striking: Many college-educated white voters seem to be deserting Trump, in large enough numbers that it could put the election out of reach for him, particularly when combined with his huge deficits among African-Americans, Latinos, and Asian-Americans. The latest ABC News/Washington Post poll shows Trump trailing Hillary Clinton 50-44 among college-educated whites, and losing women in that group by nearly 20 points. New NBC/Wall Street Journal/Marist polls in Iowa, Ohio, and Pennsylvania show Trump’s support among college-educated whites plunging since before the conventions, leaving him trailing by 31, 8, and 21 points in those states respectively.

It isn’t hard to figure out why Trump wouldn’t do as well as previous Republican nominees among this group, even if he’s offering the same tax cuts and regulatory rollback they did. As Ron Brownstein wrote not long ago, “Polls have also shown college-educated whites are much more positive than their blue-collar counterparts toward trade, immigration, and America’s growing racial diversity — all of which makes them a difficult audience for Trump’s insular agenda of defensive nationalism.”

If we accept that racial minorities are lost to Trump, the only way he could make up for not winning college-educated whites (and winning them bigly, as he’d say) would be to run up enormous numbers among the working-class whites who make up much of his base. The problem is that he’s already got them, and doesn’t have much room to grow. Barack Obama lost them by 26 points in 2012 and still won comfortably. That’s because they’re declining as a proportion of the population with each passing year, because of fast-growing minority populations and increasing levels of education.