Article II, Section 8 of the Constitution states that before the start of a presidential term, the president “shall take” the oath of office, including a promise to “preserve, protect and defend the ...

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 ...

And I’m guessing he recalls how during that ceremony he held up his right hand and swore an oath that was administered ... I will faithfully execute the Office of President of the United States ...