The governor of Wisconsin has said he wants to stop defending the state’s domestic partnership registry for gay couples.
Scott Walker, a Republican, told a judge he believes the law is unconstitutional because it mimics marriage.
The law is in court because a conservative group, Wisconsin Family Action, filed a lawsuit last summer claiming that it violates the state’s constitutional ban on gay marriage.
Supporters of the law say that although it gives gay couples the right to visit each other in hospital, inherit property and make medical decisions, it is not the same as marriage.
The previous governor, Democrat Jim Doyle, introduced the law and had asked Dane County Circuit Judge Daniel Moeser to uphold it.
Mr Walker inherited the case when he took over in January and filed a motion with Judge Moeser last week asking him to withdraw the defence.
He cited a legal opinion written two years ago by Republican Attorney General J.B. Van Hollen which said domestic partnerships are unconstitutional because they mimic marriage.
Gay rights groups Fair Wisconsin and Lambda Legal have joined the case as interveners and will continue defending domestic partnerships.
Katie Belanger, the chief executive of Fair Wisconsin, told the Washington Post: “It wasn’t unanticipated that Gov Walker would be changing his position. It’s certainly disappointing that our governor is not working to continue to allow same-sex couples to have basic protections. We’re still very confident the registry is legal.”