"President Obama is moving us forward," the ad says. "Mitt Romney would take us back."
In a sense, Obama is the one going back, returning to a position he took as a political novice in 1996. But the same changes in public opinion that made it thinkable for him to stop equivocating on gay marriage present a challenge to Romney as he repositions himself for the general election.
Sixteen years ago, when Obama...











Romney's Gay Marriage Challenge