United States presidential transition in the context of "Interregnum"

The president-elect of the United States is the candidate who has presumptively won the United States presidential election and is awaiting inauguration to become the president. There is no explicit indication in the U.S. Constitution as to when that person actually becomes president-elect, although the Twentieth Amendment uses the term "president-elect", thereby giving the term constitutional basis. It is assumed the Congressional certification of votes cast by the Electoral College of the United States – occurring after the third day of January following the swearing-in of the new Congress, per provisions of the Twelfth Amendment – unambiguously confirms the successful candidate as the official "president-elect" under the U.S. Constitution. As an unofficial term, president-elect has been used by the media since at least the latter half of the 19th century and was in use by politicians since at least the 1790s. Politicians and the media have applied the term to the projected winner, even on election night, and very few who turned out to lose have been referred to as such.

While Election Day is held in early November, formal voting by the members of the Electoral College takes place in mid-December, and those votes are later delivered to a joint session of the Congress to be counted and certified, and the presidential inauguration (at which the oath of office is taken) is then usually held on January 20. The only constitutional provision pertaining directly to the person who has won the presidential election is their availability to take the oath of office. The Presidential Transition Act of 1963 empowers the General Services Administration to determine who the apparent election winner is, and provides for a timely and organized sequence for the federal government's transition planning in cooperation with the president-elect's transition team; it also includes the provision of office space for the "apparent successful candidates". By convention, during the period between the election and the inauguration, the president-elect actively prepares to carry out the duties of the office of president and works with the outgoing (or lame duck) president to ensure a smooth handover of presidential responsibilities. Since 2008, incoming presidents have also used the name Office of the President-Elect to refer to their transition organization, despite a lack of formal description for it.

The Twentieth Amendment (Amendment XX) to the United States Constitution moved the beginning and ending of the terms of the president and vice president from March 4 to January 20, and of members of Congress from March 4 to January 3. It also has provisions that determine what is to be done when there is no president-elect. The Twentieth Amendment was adopted on January 23, 1933.

The amendment reduced the presidential transition and the "lame duck" period, by which members of Congress and the president serve the remainder of their terms after an election. The amendment established congressional terms to begin before presidential terms and that the incoming Congress, rather than the outgoing one, would hold a contingent election if the Electoral College deadlocked regarding either the presidential or vice presidential elections.

The presidential transition of George W. Bush took place following the 2000 United States presidential election. It started after Bush was declared the victor of the election on December 12, 2000, when the Bush v. Gore decision by the Supreme Court halted the election recount in Florida, making Bush the victor in that state. The decision delivered him the state's 25 electoral votes, thus giving him a total of 271 electoral votes. This was one more vote than the 270 needed to win the presidency outright, making him president-elect.

Due to the recount effort and litigation between Bush and his presidential opponent Al Gore leaving the outcome of the election unclear until December 12, 2000, Bush's official transition was abbreviated, at just 39 days. The transition was chaired by vice president-elect Dick Cheney.