Don't take it from us, take it from Politico -- Obama's support of same-sex marriage is going to hurt him in key swing states:

If there’s been one constant over the course of President Barack Obama’s evolution on gay marriage, it’s this: The White House’s keen awareness of the radioactive politics of the issue.

Obama aides fretted that delay would dent his new-breed brand, and likewise that plunging in could weigh him down in battleground states. They even hatched a plan to announce his support just prior to the Democratic National Convention — a characteristically all-in-good-time solution that acknowledged the minefield he was walking through.

And the White House is right to be concerned.

No doubt, Obama gets some political pluses out of supporting same-sex marriage Wednesday — energizing LGBT voters and donors, adding a new line to his Mitt Romney’s-a-throwback brief, kick-starting college turnout or in simply reminding people that yes, he came to Washington to do big things.

But for all the polls showing movement toward greater public acceptance of gay marriage, for all the signs of increased tolerance and changing mores, there’s one undeniable fact: A full embrace of gay rights has never been a winner in the political arena.

Fifteen years of ballot measures in more than 30 states from coast-to-coast show an issue that has been rejected nearly every time it’s gone before the voters — often by large margins.

Here are seven states where Obama just bought himself headaches with his historic decision to back gay marriage...

They are: North Carolina, Florida, Colorado, Nevada, Iowa, Missouri, and Ohio.