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.
March 30, 1981, after Ronald Reagan was hospitalized. 
Every position must be held to the last man. There must be no retirement. With our backs to the wall, and believing in the justice of our cause, each one of us must fight to the end.Alexander Haig
That's not a lie, it's a terminological inexactitude.Alexander Haig