He was elected to the Oregon State Senate from Gilliam County in 1904 and was reelected four years later. He served as president of that body from 1909 to 1911. When Governor Frank W. Benson was incapacitated by ill health in June 1910, he asked Bowerman. as President of the Senate, to assume gubernatorial responsibilities. On June 16, 1910, at age thirty-three, Bowerman became Acting Governor. 