South Carolina Senator Lindsey Graham said on Monday that the United States must “move forward” if the Supreme Court strikes down state bans on gay marriage.

The nation's highest court heard arguments last week in a case challenging bans in four states. A ruling is expected in June.

Graham, a possible candidate for the 2016 Republican presidential nomination, made his remarks during an appearance on Boston Herald Radio, BuzzFeed News reported.

“Well, can you be for traditional marriage?” Graham rhetorically asked. “Yes. Am I for traditional marriage? Yes. I believe marriage has stood the test of time between a man and a woman, ordained by God, and that's – most societies have been organized around that concept.”

“Things are changing, so at the end of the day, being for traditional marriage without animosity is where I stand. If the Supreme Court rules sometime this year that same-sex marriage bans are unconstitutional, then that will be a defining moment in that debate. It will be time for us to move forward as a society.”

Graham said that altering the U.S. Constitution to include a heterosexual only definition of marriage was unlikely. Texas Senator and presidential candidate Ted Cruz has introduced such a proposal.

“I just don't see how you get a constitutional amendment defining marriage as between a man and a woman ratified by three-fourths of the states, given the way the lay of the land is today,” Graham said.

“But at the end of the day, this whole social structure that's changing is part of democracy, is part of society,” he added.