Montana Title 5. Legislative Branch § 5-2-406. Elections to fill vacancies in senate

(a) Whenever the vacancy occurs 85 days or more prior to the primary election during the second year, the same procedure as is used for senators who will be elected to full 4-year terms at that general election must be utilized.

(b) Whenever the vacancy occurs on or after the 85th day prior to the primary election, any political party desiring to enter a candidate in the general election shall select a candidate as provided in 13-10-327 and 13-38-204. A political party shall notify the secretary of state of the party nominee. A person desiring to be a candidate as an independent shall follow the procedures provided in 13-10-501 and 13-10-502. The petition for an independent candidate must be filed with the secretary of state on or before the 85th day prior to the general election.