Gay rights advocates say they plan to sue to try to force New Jersey to recognize gay marriage.
Lambda Legal and Garden State Equality say they'll announce a lawsuit on Wednesday.
The suit comes just days after New York lawmakers passed a gay marriage law.
New Jersey legislators defeated a similar bill in 2010.
The state offers civil unions, which are designed to offer the legal protections of marriage without using the word.
Advocates have long complained that civil unions don't do what they promise.
Same-sex marriage became legal in Iowa, one of five states where gay and lesbian couples can marry, after a legal battle similar to the one advocates in New Jersey are pursuing.
In Iowa, advocates successfully argued in court denying same-sex couples marriage licenses violated the liberty and equal protection clauses in the state constitution.