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.
United States presidential line of succession
of the Constitution sets three qualifications for holding the presidency. To serve as president, one must: be a natural-born citizen of the United States; be at least thirty-five years old; and be a resident in the United States for at least fourteen years.