The President-elect of the United States is the person who has won the quadrennial presidential election in the United States, but who has not yet been inaugurated as president of the United States. President-elect is also the honorific title accorded to this individual. The only constitutional provisions pertaining directly to the president-elect, address matters related to the election winner's availability to take the oath of office. Nowhere is there an unequivocal statement made of when the winner of the election actually becomes president-elect. Since the 1960s, U.S. federal law has empowered the General Services Administration Administrator to ascertain who the apparent election winner is, and to help facilitate the basic functioning of the president-elect's transition team. 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 all presidential responsibilities. 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. Likewise, if a vice president succeeds to the presidency by way of the president's death, resignation or removal (via impeachment) from office, that person does not hold the title of president-elect, as they would become president immediately. Conversely, a sitting vice president who is elected president does become president-elect.