What Is The Oath Of Office Of The President? Trump To Be Sworn In By Supreme Court Chief Justice John Roberts On Inauguration Day

Billionaire businessman Donald Trump will become the 45th U.S. president when he takes the oath of office on Friday afternoon. While the Constitution mentions the oath of office in several places, it only articulates the exact language of the presidential oath of office. Article II, section i, clause 8 of the Constitution states:

"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.'"

Trump will take the oath on a childhood Bible, as well as the Bible Abraham Lincoln and Barack Obama used to take the oath of office. Nowhere in the Constitution does it say the oath must be taken on the Bible, or any book at all. George Washington started the tradition of taking the oath on the Christian holy book, but his successor, John Adams, took the oath using a book of law. When Lyndon Johnson took the oath of office on board Air Force One after John F. Kennedy was assassinated, he used a Catholic missal that was thought to be a Bible in the chaos following the president's shooting.

Chief Justice John Roberts will administer the oath of office to Trump on Friday, as he did for both of Barack Obama's inaugurations -- although Roberts fumbled his words during Obama's 2009 inauguration, which led to the oath being administered a second time off the inauguration stage.

The chief justice traditionally administers the oath, but like the use of the Bible, this is not required by the Constitution. George Washington was sworn in by Robert Livingston, the chancellor of New York. John Adams was the first president sworn in by the chief justice of the Supreme Court.