憲法裏麵有但是

No person shall be elected to the office of the President more than twice, and no person who has held the office of President, or acted as President, for more than two years of a term to which some other person was elected President shall be elected to the office of the President more than once. But this Article shall not apply to any person holding the office of President when this Article was proposed by the Congress, and shall not prevent any person who may be holding the office of President, or acting as President, during the term within which this Article becomes operative from holding the office of President or acting as President during the remainder of such term.

By reason of the lack of a positive expression upon the subject of the tenure of the office of President, and by reason of a well-defined custom which has risen in the past that no President should have more than two terms in that office, much discussion has resulted upon this subject. Hence it is the purpose of this . . . [proposal] . . . to submit this question to the people so they, by and through the recognized processes, may express their views upon this question, and if they shall so elect, they may . . . thereby set at rest this problem.1

https://constitution.congress.gov/browse/essay/amdt22-1/ALDE_00001008/?

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