In the aftermath of his defeat, Clarke reduced his participation in party politics, focusing instead on his legal work for a time. Yet Clarke was soon back in the political arena, withdrawing from the partnership with Williamson and Cushing in 1907. His relationship with Johnson suffered after Clarke supported the successful candidacy of conservative Democrat Judson Harmon for governor in 1908; in response, when nominating a candidate for the United States Senate race in 1910 Johnson passed over Clarke in favor of Atlee Pomerene, the eventual winner. Clarke's support for the incorporation of progressive reforms into the Ohio Constitution in 1911, however, helped to restore his standing among Ohio progressives. Clarke attempted to parlay this into a second run for a United States Senate seat early in 1914, but he faced opposition in the primary from Ohio Attorney General Timothy S. Hogan and by the spring appeared to be in danger of losing the race.