Brian Brown, president of the National Organization for Marriage (NOM), has called for the impeachment of Virginia Attorney General Mark Herring over his decision to no longer defend the state's ban on gay marriage.

Herring announced his decision on Thursday, saying that he believes the ban violates the U.S. Constitution.

(Related: Virginia's Mark Herring says he was wrong to oppose gay marriage.)

In responding to the news, Brown called for Herring's ouster.

“The Attorney General swore an oath that he would 'support … the Constitution of the Commonwealth of Virginia' and faithfully discharge his duties, which include defending duly enacted laws like the state's marriage amendment,” said Brown. “Yet now Attorney General Herring is participating in a lawsuit against the very people he is sworn to represent, the citizens of Virginia who preserved marriage in their constitution. This malfeasance and neglect of duty is not only a disgrace, it's an impeachable offense under the constitution.”

John Eastman, chairman of NOM's Board of Directors, echoed the sentiment.

“The attorney general's decision to advocate against the state's marriage law is an egregious violation of his duty,” Eastman said. “Here you don't merely have the attorney general abandoning the defense of the law and remaining neutral – a decision which itself would be based on very dubious grounds. No, this goes further: Herring is staying involved in the case, and advocating directly for the side opposed to the interests of his clients, the people of Virginia. Any other lawyer pulling that kind of nonsense would be disbarred.”