Six other states and Washington, D.C., permit gay marriage.
New Jersey recognizes civil unions, but marriage-equality advocates insist the law is flawed. They said it does not offer the legal protections of marriage, as intended. The state's main gay-rights group and same-sex couples have sued.
Democrats tried but failed to shepherd a gay-marriage bill through the Senate in the waning days of the Corzine administration in 2010 after Gov. Jon Corzine, a Democrat, said he would sign it. Fourteen senators voted for the bill.
The measure needed 21 votes to pass.
Senate President Steve Sweeney, a Democrat who abstained, has regretted not voting ever since. He has called his inaction on the bill "the biggest mistake" of his legislative career.
To indicate the importance he has since attached to the bill, Sweeney will be among its prime sponsors in the Senate along with incoming Majority Leader Loretta Weinberg and Sen. Raymond Lesniak. It is being assigned the symbolic number S1, as the first bill of the new two-year session.
"The world has changed since 2009, when the bill last came up," said Steven Goldstein, who heads the gay-rights group Garden State Equality. "I don't think anyone has seen a civil rights movement accelerate so quickly."
Democrats said they were confident they had enough votes to advance the bill, but they cannot do it by veto-proof majorities without some Republican support. The bill is likely to die with the Republican governor.
Christie also could ignore the bill if it reaches his desk, and it would become law in 45 days without his signature.