 May was elected as a New Deal Democrat to the Seventy-second Congress and to seven succeeding Congresses (March 4, 1931 – January 3, 1947).He was Chairman of the powerful Committee on Military Affairs during the Seventy-sixth through Seventy-ninth Congresses, and a consistent supporter of the Franklin D. Roosevelt administration.During World War II, May became involved with Murray and Henry Garsson, New York businessmen who sought lucrative munitions contracts then being awarded by the U.S. Government.