He served as mayor of Nashville, Illinois from 1878 to 1884, and was a delegate to all State and National Democratic Conventions from 1876 to 1896. He was a member of the Illinois Senate from 1884 to 1888. Forman was elected as a Democrat to the Fifty-first, Fifty-second, and Fifty-third Congresses (March 4, 1889 - March 3, 1895). He served as chairman of the Committee on Militia during the Fifty-third Congress.