Compiled Laws, Chapter 168. Michigan Election Law § 168.532

Sec. 532. A political party whose principal candidate received less than 5% of the total vote cast for all candidates for the office of secretary of state in the last preceding state election, either in the state or in any political subdivision affected, shall not make its nominations by the direct primary method. The nomination of all candidates of such parties shall be made by means of caucuses or conventions which shall be held and the names of the party's nominations filed at the time and manner provided in section 686a of this act.  1 The term “principal candidate” of any party shall be construed to mean the candidate whose name shall appear nearest the top of the party column.