That was fast.

Less than 24 hours after President Barack Obama explicitly declared his support for same-sex marriage, becoming the first sitting American president to do so, his re-election campaign sought to capitalize with an Internet video drawing a contrast between the president and his likely Republican challenger Mitt Romney.

I indicated my view which is I don't favor marriage between people of the same gender and I don't favor unions if they're identical to marriage other than by name, Romney says in a clip displayed during the video.

The spot goes on to list some of the benefits Romney would deny same-sex couples, including sharing health insurance or being able to make emergency medical decisions for partners, and displays a clip of Romney saying states should have discretion over hospital visitation rights. (In an interview on Wednesday, Romney said he favored visitation rights.)

Also displayed is a clip of Romney saying he supports an amendment to the U.S. constitution defining marriage as being exclusively between a man and a woman. Obama had essentially taken the opposite position prior to his Wednesday announcement, in February of 2011 instructing the Department of Justice to no longer defend in court the Defense of Marriage Act, which prohibits the federal government from recognizing same-sex marriage.

While Obama cast his announcement of support for same-sex marriage as a personal decision, saying in an interview with ABC that he had been moved by friends and colleagues in loving same-sex relationships, the ad's quick release shows the Obama campaign's desire to advantageously frame a potentially divisive issue. 

Even as national polls show a small and growing majority of Americans supporting marriage equality, a majority of states have legally banned same-sex marriage. North Carolina, a state that Obama carried in 2008 and is targeting as a handful of pivotal swing states, on Wednesday resoundingly passed a constitutional amendment saying marriage between a man and a woman was the only legal union recognized by North Carolina.

Obama allies had already been attacking Romney's same-sex marriage stance in the days leading up to the president's announcement, after Vice President Joe Biden's effusive embrace of marriage equality produced a wave of scrutiny. Top campaign adviser David Axelrod alluded on Monday to Romney's support for Proposition 8, a ballot initiative that banned same-sex marriage in California (the Church of Latter Day-Saints, of which Romney is a prominent member, contributed heavily to the campaign for Prop 8.)

There couldn't be a starker contrast on this issue than with Gov. Romney, who has funded efforts to roll back marriage laws in California and other places, Axelrod said, adding that Romney would take us backward not forward.

Romney expressed support for marriage equality when he was seeking former Massachusetts senator Ted Kennedy's seat, writing a letter to an advocacy group in which he promised to make equality for gays and lesbians a mainstream concern. But he has shifted since then, and when he was serving as governor of Massachusetts he criticized a 2003 ruling by the state's highest court that determined gays are eligible to marry.