While his personal views on the matter seem to have been unchanging, it took Barack Obama the President until 2012 to publicly support same-sex marriage. The New York Times Magazine's Jo Becker chronicles the fraught years leading up to his announcement, including the time Vice President Biden got out in front of him. 

Chad Griffin, a political strategist and LGBT activist who was deeply involved with the Prop 8 case, recalls how he got Biden to accidentally offer more support than Obama was ready to give. He tells Becker that at a fundraiser in April 2012 meant to woo gay voters, he just asked Biden the question, point-blank. 

Griffin considered asking Biden about the administration’s position on [same-sex marriage] but decided not to bother — he already knew the answer. But as he watched the hosts’ two children, ages 5 and 7, press flowers and a note into Biden’s hand, he changed his mind.  ... When it was Griffin’s turn to speak, he said: "When you came in tonight, you met Michael and Sonny and their two beautiful kids. And I wonder if you can just sort of talk in a frank, honest way about your own personal views as it relates to equality, but specifically as it relates to marriage equality."

As he often does, Biden surprised the crowd with his answer. "Things are changing so rapidly, it’s going to become a political liability in the near term for an individual to say, ‘I oppose gay marriage.’ Mark my words. ... And my job — our job — is to keep this momentum rolling to the inevitable," he said. After that, Biden did a TV interview with NBC's David Gregory where he really got out in front of the president: He confirmed his support for legal same-sex marriage, while awkwardly noting that "the president sets the policy." Obama made his support for gay couples known in a TV interview with Robin Roberts (who came out as gay earlier this year) on May 9, 2012.

The administration had planned to have Obama speak with Roberts, or another female anchor like her, even before Biden's comments — a plan which came from former RNC chair and George W. Bush strategist Ken Mehlman. Obama advisor David Plouffe reached out to Mehlman after he began working with Griffin on the Prop 8 case. Mehlman tells the Times he remembers saying, "The notion that politically [supporting same-sex marriage] is going to kill you — I don’t buy it." In addition to recommending the interview with a female host, Mehlman suggested Obama state that it was a family decision, not a political one. It worked. 

And while Biden did speak sooner than the administration would have liked, he was right about one thing — opposing gay marriage has become much more of a political liability. In 2012, half of America supported legal same-sex marriage for the first time, and that trend continues to move. Fifty-four percent of Americans now support the cause.