Sen. Rand Paul (R-Ky.) said that conservatives fighting to uphold the federal definition of marriage as between one man and one woman are going to "lose that battle."
Paul suggested in an interview on the Christian Broadcasting Network (CBN) that marriage should be defined by the states, rather than federally.
The Supreme Court is currently considering a challenge to the Defense of Marriage Act (DOMA), the federal law that defines marriage as between one man and one woman.
Paul's comments reflect the opinion shared among many libertarians, that defining marriage should be left up to the states. But conservative activists, and many GOP lawmakers, have defended the act, arguing it protects traditional marriage.
Paul said that he supports traditional marriage, calling it "important" in his CBN interview. He suggested that fighting the issue out at the state level may offer conservatives an opportunity to persuade gay-marriage supporters.
"If we were to say each state can decide, I think a good 25, 30 states still do believe in traditional marriage, and maybe if we allow the debate to go on for another couple of decades, and see if we can still win back the hearts and minds of people," he said.
However, recent polling shows support for gay marriage at an all-time high, particularly among young people, with a majority of Republicans between 18 and 29 expressing support for legalizing it.
A wave of lawmakers have come out in support of it in recent weeks, including nearly every Democrat in the Senate and two GOP senators.
Paul made no indication he's moving toward supporting gay marriage in the interview, but does seem to be open to a repeal of DOMA. His nuanced position may reflect the fact that he's considering a run for president in 2016, at which point there may be enough momentum in favor of gay marriage to cause at least one Republican presidential contender to come out in favor of legalizing it.
Paul did say he was thinking about running in the CBN interview, but hadn't decided yet.
"I think I'm in a position to be part of the solution to try to help the country to grow again and find its way, and I do want to be part of that. And so I think we'll sort that out over the next couple of years and figure that out. But we don't have an answer yet on whether that means I'll do it still as a senator from Kentucky, or whether I might be running for president," he said.