COLUMBIA, S.C. - Debate will continue at the Statehouse this week on a proposal to change the state constitution to ban same-sex marriages - something state law already does.

The South Carolina House is likely to approve the constitutional amendment on Wednesday. But whether South Carolinians actually get to vote on the issue could be in the hands of one Democratic state senator who doesn't believe the constitution is the place to legislate moral values.

"I'm not going to let others trample on the rights of gays and lesbians," said Sen. Robert Ford, D-Charleston, chairman of the Senate Judiciary Subcommittee that will take up the proposed amendment.

Supporters feel confident they can pass the amendment in the Senate - if they can get the measure out of Ford's committee. Ford plans to hold a lengthy series of public hearings that don't begin for another month.

In 1996, the General Assembly adopted a law banning gay marriage. But supporters think that statute, which limits marriage to a union between a man and a woman, does not go far enough. Advocates see the proposed constitutional amendment, approved last week by the House Judiciary Committee, as an attempt to strengthen the law.

Putting it in the constitution makes it more difficult to change. The proposed amendment is directed against states such as Massachusetts, where same-sex weddings have been sanctioned.

"This amendment gives us one extra layer of protection against a federal judiciary gone wild," said state Rep. John Graham Altman, R-Charleston.

More than a dozen states have similarly changed their constitutions, and another 23 are in the process of doing so.

Rep. James Smith, D-Columbia, opposed the measure in the House committee.

"Personally, I'm opposed to gay marriage," he said. "Marriage is between a man and a woman. But I don't believe it ought to be written into our constitution."

Smith said the amendment was a political ploy to benefit Republicans. "It's largely a get-out-the-vote effort designed to play on people's fears and biases for the purpose of political gain. I'm not going to participate in it."

The proposed constitutional amendment requires approval by two-thirds of the House and Senate, the signature of Gov. Mark Sanford and a simple majority vote of the people.

Rep. Greg Delleney, R-Chester, the measure's chief sponsor, said the resolution would clear the House by a substantial margin.

"This tells other courts, like the U.S. Supreme Court, that marriage ought to be defined the way it has always been defined since Genesis," Delleney said.

If adopted by the General Assembly, the amendment would be submitted to the people for a vote in 2006, a gubernatorial election year.

"This gives the people an opportunity to express their opinion and to see if they support the ban," Delleney said.