U.S. Constitution, Article I Section 3 Paragraphs 4 and 5:
"The Vice President of the United States shall be President of the Senate, but shall have no Vote, unless they be equally divided.
"The Senate shall chuse their other Officers, and also a President pro tempore, in the Absence of the Vice President, or when he shall exercise the Office of President of the United States."
Or, in the case of Alzheimer's joe, 'exorcise' the office. :cheesy: