Compiled Laws, Chapter 168. Michigan Election Law § 168.598

Sec. 598. (1) The state central committee of each political party shall, at least 60 days before the August primary, forward by mail to the chairperson of each county committee of the political party a copy of the call for the fall state convention of the political party, showing the number of delegates to which each county is entitled in the state convention of the political party. The state central committee shall apportion the delegates to the several counties in proportion to the number of votes cast for the candidate of the party for secretary of state in each county, respectively, at the last preceding November general election.

(2) In addition to the number of delegates allocated to each county under subsection (1), the state central committees shall allocate an additional number of delegates equal to the number of incumbent legislators nominated by their party and residing in the county.