<P> The Senate shall chuse (sic) their other Officers, and also a President pro tempore, in the Absence of the Vice President, or when he shall exercise the Office of the President of the United States . </P> <P> Clause five provides for a President pro tempore of the Senate, a Senator elected to the post by the Senate, to preside over the body when the Vice President is either absent or exercising the Office of the President . </P> <P> Although the Constitutional text seems to suggest to the contrary, the Senate's current practice is to elect a full - time President pro tempore at the beginning of each Congress, as opposed to making it a temporary office only existing during the Vice President's absence . Since World War II, the senior (longest serving) member of the majority party has filled this position . As is true of the Speaker of the House, the Constitution does not require that the President pro tempore be a senator, but by convention, a senator is always chosen . </P> <P> The Senate shall have the sole Power to try all Impeachments . When sitting for that Purpose, they shall be on Oath or Affirmation . When the President of the United States is tried, the Chief Justice shall preside: And no Person shall be convicted without the Concurrence of two thirds of the Members present . </P>

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