 In 1858 he defeated incumbent Republican William Alanson Howard to be elected as a Democrat from Michigan's 1st congressional district to the Thirty-sixth Congress, serving from March 4, 1859, until May 15, 1860.Howard contested the results in the U.S. House, alleging voting irregularities in several wards.Following its investigation, the House Committee on Elections reported that the sitting member, Cooper, was not entitled to his seat and that the contestant Howard was.