North Carolina residents will vote next year on a constitutional amendment to ban same-sex marriage after the Senate on Tuesday approved putting the issue on a statewide ballot.
The 30-16 vote was enough to reach a three-fifths threshold needed to place an amendment to the state constitution on the ballot. The House approved the measure on Monday helped by the votes of 10 Democrats.
North Carolina currently has a statute defining marriage as a union between a man and a woman, but Republican leaders have pushed for a constitutional amendment to protect that law from being overturned by the courts.
North Carolina is the only Southern state that does not already have a ban on same-sex marriage enshrined in its constitution, while six states and the District of Columbia recognize gay marriage.
Supporters of the bill had originally proposed putting it on the general election ballot in November but agreed to switch the date to the May primary ballot to draw the support of Democrats whose votes were needed in the House.
Democrats had worried that having a same-sex marriage amendment on the general election ballot would skew turnout during next year's presidential contest in the Republicans' favor. North Carolina is expected to be a battleground state in 2012.
State Senator Dan Soucek, a Republican and sponsor of the amendment, said it was necessary to protect marriage between a man and a woman as the "time-tested building block of society."
Senator Ellie Kinnaird, a Democrat, said the amendment was about the oppression of gay people.
"What we are doing here is making a situation that is difficult for many people much, much worse," she said.
Several hundred gay rights advocates protested the amendment at a noon rally outside the Legislative Building in Raleigh.