There's an impasse over whether Pennsylvania Attorney General Kathleen Kane can or cannot refuse to defend the state's ban on same-sex marriage.

Kane announced Thursday that she believes the law is unconstitutional and will not defend it against a lawsuit by the American Civil Liberties Union and a group of Pennsylvania residents.

Members of Pennsylvania's Republican caucus have signed a letter accusing Kane of ignoring her "constitutional and statutory duty to defend Pennsylvania laws."

"She's just going on her personal opinion, really her personal bias, in a sense," said the House GOP spokesman Steve Miskin.

He predicted his party will continue to argue Kane is required to defend the state law in court.

"I would expect this issue to continue. I mean, what other law is she going to just choose not to defend?" he said Friday. 

Kane has deferred in this case to the governor's office. She responded to the letter in a statement Friday that her office passes on cases "hundreds of times each year, for many different reasons."

"I swore an oath that I would defend and obey the constitution," she wrote. "What I did yesterday was simply that. I was obeying the constitution."