This undated combination photo shows Republicans Clark Durant (left) and former Rep. Pete Hoekstra, who were running in the Aug. 7, 2012, Michigan GOP primary. Mr. Hoekstra was declared the winner and will take on Democratic Sen. Debbie Stabenow in November. (AP Photo)

This undated combination photo shows Republicans Clark Durant (left) and former Rep. Pete Hoekstra, who were running in the Aug. 7, 2012, Michigan GOP primary. Mr. Hoekstra was declared the winner and will take on Democratic Sen. Debbie Stabenow in November. (AP Photo)