Idaho Code § 34-1504
Each elector of president and vice-president of the United States shall, before the hour of twelve (12) o'clock on the day next preceding the day fixed by the law of Congress to elect a president and vice-president, give notice to the governor that he is at the seat of government and ready at the proper time to perform the duties of an elector; and the governor shall forthwith deliver to the electors present a certificate of all the names of the electors; and if any elector named therein fails to appear before nine (9) o'clock on the morning of the day of election of president and vice-president as aforesaid, the electors then present shall immediately proceed to elect, by ballot, in the presence of the governor, persons to fill such vacancies.
Idaho Code § 34-1504