Opponents of the statewide marriage amendment rallied at a downtown Charleston church Friday, and while their hope of victory remains slim, they took heart in the growing coalition they have built and vowed that their real work will begin after election day.

Christian and Jewish leaders joined with labor, civil liberties and other groups on the steps of the Circular Congregational Church to urge voters to reject Amendment No. 1, which asks if a marriage between one man and one woman should be the only lawful domestic union valid in South Carolina.

The amendment is widely expected to pass by a large margin. At a Thursday campaign rally, Lt. Gov. Andre Bauer, who supports the amendment, said he expects it to gain 75 percent of the vote.

If voters reject the amendment, nothing will change. If they approve the amendment, little also is expected to change because South Carolina already has a 1996 law that restricts marriage to unions between a man and a woman. Some say the amendment's real purpose is to give conservatives added incentive to go to the polls.

The amendment also has had another effect: uniting the state's gay, lesbian, bisexual and transgender community with other religious and civic groups that support some of its goals.

Stephanie Tranen of Hadassah, Women's Zionist Organization of America, said her group doesn't take a stand on gay marriage but added, "We believe same-sex couples deserve equal protection under the law."

The Rev. Bert Keller of Circular Congregational urged voters to reject the amendment because it "is clearly designed to harm people." The Rev. Peter Lanzillotta of the Unitarian Church of Charleston agreed: "To vote against this amendment is a step for compassion, freedom and inclusiveness."

Asha Leong, who is managing the anti-amendment campaign for the S.C. Equality Coalition, said her group takes heart that their movement has been backed by other voices, from NAACP chairman Julian Bond, who did a radio spot against it, to the American Civil Liberties Union, the AFL-CIO of South Carolina and the National Association of Social Workers.

The Charleston Metro Chamber of Commerce also came out against it this week, saying it could keep away gay and lesbian workers from other states, hurting the ability of local businesses to recruit workers. Chamber CEO Charles Van Rysselberge said, "This kind of a message says 'This is not a friendly atmosphere,' " he said, adding that the chamber isn't condoning same-sex marriage, just opposing the amendment.

Kyle Stock contributed to this report.