Mich. Comp. Laws § 168.732
Authority signed by the recognized chairman or presiding officer of the chief managing committee of any organization or committee of citizens interested in the adoption or defeat of any measure to be voted for or upon at any election, or interested in preserving the purity of elections and in guarding against the abuse of the elective franchise, or of any political party in such county, township, city, ward or village, shall be sufficient evidence of the right of such challengers to be present inside the room where the ballot box is kept, provided the provisions of the preceding sections have been complied with. The authority shall have written or printed thereon the name of the challenger to whom it is issued and the number of the precinct to which the challenger has been assigned.
MCL 168.732