George W. Bush is promising that if he is elected he will put his hand on the Bible and add to the presidential oath that he will "uphold the honor and the dignity of the office." Can a president revise the oath?
No. It's not a wedding vow, it's a constitutionally mandated oath. Article II, section 1, clause 8 of the Constitution requires the president to say: "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." No one has ever deviated from the text. Even though Quakers object to swearing oaths, all presidents, even Quakers Richard Nixon and Herbert Hoover, have chosen the "swear" option. Since the oath only requires a president to faithfully execute the office, not be faithful to his wife, Bush's suggested addition (let's call it the "Monica clause") would require a constitutional amendment.
While "So help me, God," is the familiar ending to the oath, it is not required. This was spontaneously added at the first inaugural by George Washington. Not wanting to mess with success, every subsequent president has said it. (The vice presidential oath, which is set out in the U.S. Code, does mandate the phrase.) A hand on the Bible is a custom from the British but not required, though all presidents have done it. Washington delivered a post-swearing-in inaugural address, which has also become standard except when vice presidents take over because of the death of the president.
Being sworn in at the Capitol by the chief justice is a matter of tradition, not law. Washington was sworn in New York City where the first Congress met. The ceremony didn't move to the Capitol until Jefferson's inaugural in 1800. During World War II Roosevelt moved it to the White House because he felt a big celebration was inappropriate. Lyndon Johnson was sworn in by a federal judge aboard the presidential plane at Love Field in Dallas after the assassination of John F. Kennedy. And Ronald Reagan's second inauguration was moved to the Rotunda because of cold weather.
Explainer thanks Donald Ritchie of the Senate Historical Office and Slate readers Scott Peters and Animal J. Smith for suggesting the question.