A U.S. Marine is facing possible dismissal from the military for his Facebook page that is critical of the president.

Marine Sergeant Gary Stein says on the page, Armed Forces Tea Party, that he has followed Defense Department rules on what political activities are permitted for members of the military. The Marines have told Stein that he is in violation of the policy.

The California-based Marine says he is only exercising his constitutional right to free speech, and has never spoken on behalf of the Marine Corps or while in uniform. Stein says he will not follow what he calls any unlawful order by the president, the commander-in-chief of the military.

The Pentagon prohibits members of the military from participating in political events if they act or would be perceived as representing the armed forces. Military members cannot attend political events in uniform, give public political speeches, serve in any official capacity in partisan groups or participate in partisan political campaigns or conventions.