Idaho Code § 34-419

The county clerk shall remove from the register of electors the official registration application of any elector who appears by the registration records in the office of the county clerk not to be a citizen of the United States and shall suspend the registration of such elector. The county clerk shall mail a written notice of such removal and suspension to the elector at his residence address indicated on the application. If the elector proves to the county clerk that he is in fact a citizen of the United States, his application shall be replaced in the register and his registration reinstated.