Mich. Comp. Laws § 168.535

Sec. 535. A general primary shall be held in every election precinct in this state on the Tuesday succeeding the first Monday in August preceding every general November election, at which time the qualified and registered voters may vote for nonpartisan candidates for the office of judge of the court of appeals, judge of the circuit court, judge of probate and for circuit court commissioner in the years in which such officers are to be elected.