The president-elect of the United States is the candidate who has 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", thus giving the term "president-elect" constitutional justification. 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 have lost 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 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. Incumbent presidents who have won re-election for a second term are generally not referred to as presidents-elect, as they are already in office and are not waiting to become president. A sitting vice president who is elected president is referred to as president-elect.