<Li> Article II, Section 1, Clause 6 makes the vice president first in the line of succession and allows the Congress to provide by law for cases in which neither the president nor vice president can serve . </Li> <Li> The 12th Amendment includes a statement clarifying that, just as they would due to the president's death or disability, the powers and duties of the presidency devolve to the vice president if--following a presidential election where no candidate won an absolute majority of votes in the Electoral College--the House of Representatives has been unable to elect a president by the scheduled beginning of the president's term . </Li> <Li> The 20th Amendment, Section 3, supersedes the above 12th Amendment provision, by declaring that if the president - elect dies before his term begins, the vice president - elect becomes president on Inauguration Day and serves for the full term to which the president - elect was elected, and also that, if on Inauguration Day, a president has not been chosen or the president - elect does not qualify for the presidency, the vice president - elect acts as president until a president is chosen or the president - elect qualifies . It also authorizes Congress to provide for instances in which neither a president - elect nor a vice president - elect have qualified . </Li> <Li> The 25th Amendment, Section 1, clarifies Article II, Section 1, Clause 6, by stating unequivocally that the vice president is the direct successor of the president, and becomes president if the incumbent dies, resigns or is removed from office . It also, in sections 3 and 4, provides for situations where the president is temporarily disabled, such as if the president has a surgical procedure or becomes mentally unfit . Additionally, in Section 2, the amendment provides a mechanism for intra-term vice presidential succession, establishing that vice presidential vacancies will be filled by the president and confirmed by both houses of Congress . Previously, whenever a vice president had succeeded to the presidency or had died or resigned from office, the vice presidency remained vacant until the next presidential and vice presidential terms began; there were 16 such vacancies prior to 1967 . </Li>

Who is 4th in command of the usa