Oath Of Office

Before he enter on the Execution of his Office, he shall take the following Oath or Affirmation: -- "I do solemnly swear (or affirm) that I will faithfully execute the Office of President of the United States, and will to the best of my Ability, preserve, protect and defend the Constitution of the United States."

-- Presidential oath of office, from the Constitution of the United States, Article II, Section 1

This oath differs from the oath of office used since 1884 by the vice president, senators, representatives, and other federal employees, including your humble editor 4 decades past, to wit, "I 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."