Among the responsibilities which the Constitution imposes upon Congress is the regulation of the succession to the office of president in certain contingencies. The framers of the Constitution themselves disposed of the problem in part by creating the post of vice-president and making that officer a first recourse in filling a vacancy in the presidential office. Realizing the need for designating more than one prospective successor, since vacancies might occur in both offices simultaneously, the convention at a late stage in its proceedings added as a seeming afterthought a clause authorizing Congress to make further provision by law on the subject. Although seven presidents and seven vice-presidents have died in office and one vice-president has resigned during the time the Constitution has been in operation, the situation envisaged by the framers has never actually arisen. Nevertheless, the power entrusted to Congress is important potentially. During nearly one-fourth of the time since 1789, a federal statute rather than a constitutional provision has governed the succession to the presidential office in an immediate sense.
Two fundamentally opposed theories have been advanced concerning the officer upon whom Congress should cause the powers and duties of the presidency to devolve. One is that the presiding officer of the House or the Senate should be designated, in order to insure that any person becoming acting president shall achieve that status through an elective process.