Oath of office of the Vice President of the United States

The Oath of office of the Vice President of the United States is the oath or affirmation that the Vice President of the United States takes upon assuming the vice-presidency but before he or she begins the execution of the office. Just before the president-elect takes the oath of office on Inauguration Day, the vice president-elect will step forward on the inaugural platform and repeat the oath of office. Although the United States Constitution—Article II, Section One, Clause 8—specifically sets forth the oath required by incoming presidents, it does not do so for incoming vice presidents. The constitution—Article VI, Clause 3— simply requires that they, along with all other government officers (federal and state; elected and appointed), pledge to support the Constitution. Since 1937 Inauguration Day has been January 20 (was March 4), a change brought about by the 20th amendment to the Constitution, which had been ratified four years earlier. The vice president's swearing-in ceremony also moved that year, from the Senate chamber inside the Capitol, to the presidential inaugural platform outside the building.

I, AB, do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.

...
Wikipedia