There are more white voters than people think. That's good news for Trump.

These sources show a 2012 electorate that was far whiter, older and less educated than the exit polls indicated.

Over all, the exit polls suggest that 23 percent of voters in 2012 were white, over age 45 and without a college degree. Catalist puts this group at 29 percent, and the census at 30 percent — implying 10 million more voters than the 23 percent figure…

The larger number of white working-class voters implies that Democrats are far more dependent on winning white working-class voters, and therefore more vulnerable to a populist candidate like Mr. Trump.

Over all, 34 percent of Mr. Obama’s supporters were white voters without a college degree, compared with 25 percent in the exit polls, according to an Upshot statistical model that integrated census data, actual results and 15,000 interviews from various pre-election surveys. The model yields a full alternative to the exit polls that assume an older, whiter electorate like the one depicted by the census. (For those interested in the details about our estimates, we’ve written a technical sidebar.)…

All of this is good news for a Republican who intends to win with greater strength among white working-class voters, like Mr. Trump.

There is a downside for him. The lower turnout among Hispanic and young voters implies that it’s possible — even easy — to imagine a huge increase in Hispanic and youth turnout in 2016. And Mr. Obama’s strength among Northern white voters raises doubts about whether the Republicans, including Mr. Trump, can assume that white working-class voters are receptive to conservative candidates…

Even if the missing white voters were disproportionately Republican, a return to previous turnout levels wouldn’t have been anywhere near enough to get Mr. Romney over the top. There were far fewer missing white voters in the battleground states than there were nationally. There weren’t close to enough of them to flip the outcome in key states.

The real pool of missing white voters are those who haven’t participated in any recent election, or aren’t even registered to vote. There are millions of these missing white voters — but they will be much harder to mobilize. Many are young, and might not be especially favorable to Mr. Trump. The older ones are true bystanders in American politics.