Mich. Comp. Laws § 168.95
If a candidate of a political party for the office of United States senator, after having qualified as a candidate, dies after the last day for qualifying, leaving the political party without a candidate for the office of United States senator, a candidate to fill the vacancy may be selected by the state central committee and the name of the candidate selected shall be transmitted to the secretary of state and to the county officials required by law to print and distribute ballots. The name of the candidate shall be printed on the ballots, but if the ballots have been printed, the county officials shall have the ballots reprinted with the candidate's name on the ballots and the reprinted ballots shall be distributed to the various voting precincts within their respective counties.
MCL 168.95