Montana Constitution Art. VI, § 6. Vacancy in office

(1) If the office of lieutenant governor becomes vacant by his succession to the office of governor, or by his death, resignation, or disability as determined by law, the governor shall appoint a qualified person to serve in that office for the remainder of the term. If both the elected governor and the elected lieutenant governor become unable to serve in the office of governor, succession to the respective offices shall be as provided by law for the period until the next general election. Then, a governor and lieutenant governor shall be elected to fill the remainder of the original term.

(2) If the office of secretary of state, attorney general, auditor, or superintendent of public instruction becomes vacant by death, resignation, or disability as determined by law, the governor shall appoint a qualified person to serve in that office until the next general election and until a successor is elected and qualified. The person elected to fill a vacancy shall hold the office until the expiration of the term for which his predecessor was elected.