The primary election selected the candidates from each party to run in the general election for lieutenant governor of Idaho took place on May 15, 2018.

[2] On March 3, 2018, Bob Nonini reportedly nodded when asked at a candidates forum if the punishment for getting an abortion should include the death penalty.

Idaho's closed primary election allows only registered Republicans and unaffiliated voters the option of voting to select the next Republican candidate for lieutenant governor.

Any registered or unregistered voter may vote in the Democratic primary to select the next lieutenant governor candidate from the two candidates running.

Idaho has a same-day voter registration system which allows any voter to register to vote at a polling place on election day.