Newt Gingrich has conceded that momentum is on the side of supporters of gay marriage.

While not endorsing gay nuptials, Gingrich, the former House Speaker and a leading candidate for the 2012 GOP presidential nomination, told The Huffington Post that he was prepared to accept “a legal document issued by the state” for gay and lesbian couples.

“I think that this will be much more difficult than immigration for conservatism to come to grips with,” he said after referencing the results of the November 6 election. “It is in every family. It is in every community. The momentum is clearly now in the direction in finding some way to … accommodate and deal with reality. And the reality is going to be that in a number of American states – and it will be more after 2014 – gay relationships will be legal, period.”

Gingrich, who has a gay half sister, said he has married gay friends. He added that he fears that the issue could hurt the Republican Party, whose official platform opposes the legalization of marriage equality.

“I didn't think that was inevitable 10 or 15 years ago, when we passed the Defense of Marriage Act,” he said. “It didn't seem at the time to be anything like as big a wave of change as we are now seeing.”

During the campaign, Gingrich reiterated his support for an amendment to the U.S. Constitution defining marriage as a heterosexual union and described gay nuptials as pagan behavior.