Republican White House hopeful Mitt Romney firmly rejected same-sex marriage yesterday in a major address at the nation’s biggest Christian university.

Marriage is a relationship between one man and one woman

Three days after President Barack Obama voiced support for gay and lesbian marriage, Romney said the “pre-eminence of the family” was the cornerstone of the principles that underpin American culture .

“As fundamental as these principles are, they may become topics of democratic debate,” the presumptive Republican nominee told freshly minted graduates at Liberty University.

“So it is today with the enduring institution of marriage. Marriage is a relationship between one man and one woman,” he said in a grave voice, raising a loud cheer from the crowd.

Romney – who refrained from directly referring to homosexuality, gays or lesbians in his speech – has previously stated he is against gay marriage, but says same-sex couples should have some rights such as child adoption.

Virginia is a key battleground in November’s presidential election. First Lady Michelle Obama pre-empted Romney by delivering her own commencement speech at another university less than 145 kilometres from Lynchburg.

With Obama’s landmark public endorsement of same-sex marriage, and a fundraiser at Hollywood star George Clooney’s home raising $15 million, Romney chose to tout family values aiming set himself apart from his incumbent rival.

With so many Christian graduates in his audience, Romney stressed faith and “the commitments of family,” in a speech with strong references to God and what he called America’s Judeo-Christian tradition.”

“Take those away, or take them for granted, and so many things can go wrong in a life. Keep them strong, and so many things will go right,” he said.