Backers of a proposed North Carolina constitutional amendment defining marriage as only between a man and a woman predicted victory in a Tuesday vote. \"The people of the state recognize the importance of protecting marriage between a man and a woman,\" Tami Fitzgerald, who is leading the campaign in support of the amendment, told Fox News Channel. The amendment, known as Amendment 1, stipulates \"marriage between one man and one woman is the only domestic legal union that shall be valid or recognized in this state.\" The amendment would not just ban recognition of same-sex marriage, but also civil unions and domestic partnerships of any kind. \"We didn\'t want civil union to be a marriage clone,\" Republican state Sen. Dan Soucek, one of the amendment\'s primary sponsors, told Fox. \"We wanted that institution to be protected, not just the word,\" he said. About 12 percent of North Carolina domestic partnerships are between same-sex couples, 2010 U.S. Census data indicate. Evangelist Billy Graham last week urged voters to support Amendment 1. \"At 93, I never thought we would have to debate the definition of marriage,\" Graham said in a rare statement. \"The Bible is clear -- God\'s definition of marriage is between a man and a woman. \"I want to urge my fellow North Carolinians to vote for the marriage amendment,\" his statement said. Graham lives near Asheville, N.C. Recent polls show support of the measure, but opponents said they were counting on their efforts to spread awareness. The Coalition to Protect North Carolina Families, which opposes Amendment 1, has raised $2.2 million. Vote For Marriage NC, which supports the marriage-defining amendment, has raised $1.1 million. A poll conducted by Civitas Institute, a conservative think tank, projected the measure would win by 16 percentage points. A poll by Public Policy Polling, which often conducts polls for Democratic clients, indicated the measure would win by 14 points. North Carolina law already bans same-sex marriage, but the state has not changed its Constitution to ban it. Ten other Southern states have constitutional bans on same-sex marriage and, in some cases, on civil unions as well. Tuesday\'s vote is to be held along with the state\'s Democratic and Republican primaries.