The portions of the electorate that remained loyal to President Obama and Democrats—particularly minority voters and young people—did not show up in anywhere near the numbers they did in 2008. And among the voters who did show up, Democratic candidates suffered crippling defections among white voters, particularly independents, seniors, and those without a college education, according to the national network exit poll of House elections.

Young people, who cast 18 percent of the ballots in 2008, dropped to just 11 percent. That was a slightly larger falloff than is typical in midterm elections. Likewise, the falloff between the minority share of the vote in 2008 and Tuesday night was the largest decline between a presidential and the subsequent midterm election in at least the past two decades. Two years ago, minorities cast 26 percent of all ballots in the presidential election; this year that number fell to 22 percent. Both groups largely stuck with Democrats—but their impact was severely diluted by their declining turnout.

Meanwhile, seniors, who represented one-sixth of voters in 2008, soared to fully 22 percent—their largest share since at least 1992. And nearly three-fifths of them backed Republican House candidates. Among white seniors, that number rose to over three-fifths.

Overall, the national exit poll measuring preferences in House races put the Republican vote among whites at a jaw-dropping 60 percent, up sharply from 53 percent in 2008. Democratic candidates attracted only about 35 percent of the vote among white men and women without a college education and college-educated white men. Following patterns evident in Obama’s approval rating, the only segment of the white electorate that didn’t collapse for Democrats were college-educated white women. But even they tilted slightly toward the GOP.

In a geographic reflection of Obama’s weakness among blue-collar white voters, a partial count showed that Republicans captured the seats of at least 35 House Democrats in districts where the percentage of whites with a college degree lags the national average of 30.4 percent.