Obama has no authority in the matter. The Governor of Texas is vested with the authority of the Texas Constitution.
After having checked both the Texas *and* United States Constitutions and you'll find that the Governor of Texas does have substantial command authority over the Texas Army and Air National Guard but the President of the United States has *ultimate* command authority over every uniformed member of the United States Armed Forces...including the Texas National Guard.Osama Obama could overrule any order given by Perry with a 30 second phone call.So could the Secretary of the Army or the Secretary of the Air Force.