In the 1876–1877 electoral college crisis, he helped to arrive at the solution of creating the Electoral Commission to settle the controversy, and ultimately served as one of the members of the commission, as one of the five Senators (one of the two Senate Democrats, and one of the seven Democrats altogether). As a Democrat, he voted with the seven-member minority, in favor of the Samuel J. Tilden electors in all cases, but the Republican majority prevailed in all the votes, and Thurman's 1867 gubernatorial opponent, Rutherford B. Hayes (who had returned to the governorship by defeating Thurman's uncle), became president. (One of the House of Representatives' members of the Commission, fellow Ohioan James Garfield, was to become the president four years later, after being chosen by the now-Republican Ohio legislature to succeed Thurman. Both men were lifelong friends.)