The oaths or affirmations required by the Constitution and prescribed by law shall be taken and subscribed by each Senator, in open Senate, before entering upon his duties.
OATH REQUIRED BY THE CONSTITUTION AND BY LAW TO BE TAKEN BY SENATORS
"I, A__ B__, 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." (5 U.S.C. 3331.)