Idaho constitution
Article XXI
Section 14

The governor elect
of the state, immediately upon his qualifying and entering upon the duties of
his office, shall issue his proclamation convening the legislature of the state at the
seat of government on a day to be named in said proclamation and which shall not
be less than thirty (30) nor more than sixty (60) days after the date of such
proclamation. Within ten (10) days after the organization of the legislature, both
houses of the legislature shall then and there proceed to elect, as provided by law,
two (2) senators of the United States for the state of Idaho. At said election, the
two (2) persons who shall receive the majority of all votes cast by said senators and
representives [representatives], shall be elected as such United States senators, shall
be so declared by the presiding officers of said joint session. The presiding officers
of the senate and house, shall issue a certificate to each of said senators, certifying
his election, which certificates shall also be signed by the governor and attested by
the secretary of state.