The text messages ask for your vote on the two propositions on the ballot. Some of them even address you by name.
The clerk of the district court says when you register to vote in Idaho, you put your information such your name and address. Companies that are actively working to campaign can purchase that information and they can use it to contact you in a variety of ways.
Listing your phone number on that registration form in Idaho is optional.
"The text messages is just a recent reiteration of contacting voters so but if they've got the phone number there, they can probably match your phone number with a name and they can also see what political party you belong to and how frequently you vote to so it gives them some information to dial in a little bit on contacting voters," said Chris Rich, clerk of the district court.
If you know the group itself that is sending the text messages, you can contact them directly to remove your phone number.
You can also contact the secretary of state's office or go to their website to find out all the groups that have initiatives on the ballot.