The president said his views had "evolved" after years of discussions with friends, family and staff on the issue, citing "members of my own staff who are in incredibly committed monogamous relationships, same-sex relationships, who are raising kids together."
While Democrats were quick to rally around the president's statement, Republicans have so far been slow to comment on Obama's comments.
Presumptive Republican presidential nominee Mitt Romney told reporters he wouldn't discuss the president's comments "on the rope line" after an event in Colorado Wednesday morning.
But Romney did indicate in an interview earlier Wednesday that he still opposed same-sex marriage.
“Well, when these issues were raised in my state of Massachusetts, I indicated my view, which is I do not favor marriage between people of the same gender, and I do not favor civil unions if they are identical to marriage other than by name,” Romney told KDVR-TV. “My view is the domestic partnership benefits, hospital visitation rights, and the like are appropriate but that the others are not.”
Rep. Steve Stivers (R-Ohio) was among the first elected Republicans to respond directly to the president's interview, reiterating on MSNBC his belief that "marriage is between one man and one woman."