Twenty-second Amendment to the United States Constitution
The amendment prohibits any individual who has been elected president twice from being elected again. Under the amendment, an individual who fills an unexpired presidential term lasting greater than two years is also prohibited from winning election as president more than once. Scholars debate whether the amendment prohibits affected individuals from succeeding to the presidency under any circumstances or whether it only applies to presidential elections.
Acting President of the United States
Presidential succession is referred to multiple times in the U.S. Constitution, as well as the Twentieth Amendment and Twenty-fifth Amendment. The Vice President is the only officeholder named in the Constitution as a presidential successor. The Article II succession clause authorizes Congress to designate which federal officeholders would accede to the presidency in the event that the vice president were unable to do so, a situation which has occurred on three separate occasions. The current Presidential Succession Act was adopted in 1947 and last revised in 2006. The order of succession is as follows: the Vice President, the Speaker of the House of Representatives, the President pro tempore of the Senate, and then the eligible heads of the federal executive departments who form the president's Cabinet, beginning with the Secretary of State.