Idaho Const. art. III, § 25

The members of the legislature shall, before they enter upon the duties of their respective offices, take or subscribe the following oath or affirmation: "I do solemnly swear (or affirm, as the case may be) that I will support the constitution of the United States and the constitution of the state of Idaho, and that I will faithfully discharge the duties of senator (or representative, as the case may be) according to the best of my ability." And such oath may be administered by the governor, secretary of state, or judge of the Supreme Court, or presiding officer of either house.