(CBS)-- Voters in North Carolina on Tuesday voted in favor of a controversial amendment that will write a ban on same-sex marriage as well as civil unions for both gay and straight couples into the state Constitution, according to the Associated Press.
With 35 percent of precincts reporting, the amendment was passing by a 58 percent to 42 percent margin.
The amendment mandates that only "marriage between one man and one woman is the only domestic legal union that shall be valid or recognized." Opponents of the measure ran ads stressing the impact the language would have on straight North Carolina residents, arguing that the measure would eliminate protections against domestic violence.
Former President Bill Clinton campaigned against the amendment, arguing that it "will hurt families and drive away jobs," and President Obama opposed it in a statement - though the president, who is walking a careful line on same-sex marriage, did not mention the amendment during a recent visit to the state.
Supporters, like 93-year-old Rev. Billy Graham, made a more straightforward appeal: "Watching the moral decline of our country causes me great concern," he said in a newspaper ad supporting the amendment. "I believe the home and marriage is the foundation of our society and must be protected."
Polls showed that many North Carolina voters did not understand that the amendment would impact straight couples as well as same-sex couples. The state already has a law banning same-sex marriage on the books; supporters of the amendment said was necessary because the law could be struck down by judges.
With the passage of the amendment, North Carolina becomes the 30th state and final former Confederate state to write a gay marriage ban into its Constitution. Other states are going in the opposite direction: In March, Maryland became the eighth state (counting the District of Columbia) to legalize same-sex marriage.