In Florida, 238,000 more Hispanics voted than in 2008, and Mr. Obama got 60% of Hispanic voters. His total margin of victory in Florida was 78,000 votes, so that demographic alone won it for him. Or consider Ohio, where Mr. Romney won independents by 10 points. The lead mattered little, though, given that black turnout increased by 178,000 votes, and the president won 96% of the black vote. Mr. Obama’s margin of victory there was 103,000.

This is the demographic argument that is getting so much attention, and properly so. The Republican Party can hope that a future Democratic candidate won’t equal Mr. Obama’s magnetism for minority voters. But the GOP would do far better by fighting aggressively for a piece of the minority electorate.

And that, for the record, was the GOP’s real 2012 turnout disaster. Elections are about the candidate and the message, yes, but also about the ground game. Republicans right now are fretting about Mr. Romney’s failures and the party’s immigration platform—that’s fair enough. But equally important has been the party’s mind-boggling failure to institute a competitive Hispanic ground game. The GOP doesn’t campaign in those communities, doesn’t register voters there, doesn’t knock on doors. So while pre-election polling showed that Hispanics were worried about Obama policies, in the end the only campaign that these voters heard from—by email, at their door, on the phone—was the president’s.