Check Quotes - page 6
Constitutionally, gentlemen, you have the president, the vice president and the secretary of state, in that order, and should the president decide he wants to transfer the helm to the vice president, he will do so. As for now, I'm in control here, in the White House, pending the return of the vice president and in close touch with him. If something came up, I would check with him, of course.
Alexander Haig