Obama told ABC News' Robin Roberts:
"I have to tell you that over the course of several years as I have talked to friends and family and neighbors when I think about members of my own staff who are in incredibly committed monogamous relationships, same-sex relationships, who are raising kids together, when I think about those soldiers or airmen or marines or sailors who are out there fighting on my behalf and yet feel constrained, even now that Don't Ask Don't Tell is gone, because they are not able to commit themselves in a marriage, at a certain point I’ve just concluded that for me personally it is important for me to go ahead and affirm that I think same sex couples should be able to get married."
The move comes days after Vice President Joe Biden told NBC News that he was "comfortable" with gay couples marrying. Education Secretary Arne Duncan also expressed his support for same-sex unions this week.
Just yesterday, North Carolina became the last state in the South to put a gay marriage ban in their constitution after voters overwhelmingly approved a measure known as Amendment One.