Idaho Code § 59-910

Whenever any vacancy shall occur in the office of United States senator from the state of Idaho by death, resignation or otherwise, the governor shall have the power and is hereby authorized and empowered to fill such vacancy by appointment, and the person so appointed shall hold such office until such time as a United States senator is regularly elected to fill such vacancy, at the next succeeding general election, and qualifies by virtue of such election: provided, however, that in case a vacancy occurs in the position of United States senator from the state of Idaho within thirty (30) days of any general election, no election for United States senator to fill said vacancy shall be held at such general election.