The announcement will surely boost Latino support and turnout for the president, strengthening his prospects in such key swing states as Nevada, New Mexico and Colorado, and even in North Carolina and Virginia. By the same token, it magnifies Romney’s Latino problem. Much of the Republican base will want him to announce today, immediately, now, that he’ll rescind this order when he becomes president. Tea Party Republicans are committed to an anti-immigrant crusade, and they will lean on Romney particularly hard.

But if Romney does pledge to rescind the order, his already weak standing among Latino voters will grow feebler still. Latinos will turn out in droves to vote against him. I don’t doubt that thought has already occurred to Obama strategists. If they reasoned that swing white voters really didn’t have it in for children, that they were largely antagonizing voters who already didn’t like Obama, they were quite likely right.

Obama’s order hit the sweet spot for him. And put Mitt Romney in a hell of a fix.