Members of Congress (Legislative Branch)
At the start of each new Congress, in January of every odd-numbered year, the entire House of Representatives and one-third of the Senate takes an oath of office. The Speaker of the House will direct the Members to rise and the oath is administered. The original oath was as follows: "I do solemnly swear (or affirm) that I will support the Constitution of the United States."
The oath was revised during the Civil War, when members of Congress were concerned about traitors. The current oath is as follows:
"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."