Swing states are a problem for the president too. The numbers in national polls include supporters of gay marriage in states where it's already legal, like Massachusetts and New York, places Obama already has more votes there than he needs. Where he needs help is places like Ohio, Florida and Virginia, all three of which have passed gay marriage bans.
Only this week, North Carolina, a state Obama won in 2008 (and briefly hoped to win again this year), voted by a whopping 60% to approve a state constitutional amendment that outlaws not only gay marriage but also other forms of domestic partnership.
To Obama and his political advisors, it seemed to make sense, as a matter of practical politics, for the president to try to skate through this election year in his unfinished state of evolution. As long as most of his gay supporters were willing to put up with it, what was the downside?
Biden made that impossible — and at that point, Obama responded quickly. He sounded thoughtful in his interview with ABC News' Robin Roberts. He talked about conversations with "friends and family and neighbors," and with his daughters, "Malia and Sasha — they've got friends whose parents are same-sex couples." He talked about gay members of his own staff "in incredibly committed monogamous relationships."
And he talked about how knowing those people and having those conversations prompted him to change his views — just like a lot of other Americans.