Sutphin attended the public schools of Matawan, New Jersey, the Woods Business College in Brooklyn, and attended the officers training camp at Plattsburgh, New York in 1915. He was mayor of Matawan from 1915–1916 and 1921–1926. He served on the United States-Mexico border in 1916 (see Pancho Villa Expedition) with B Troop, First Squadron, New Jersey Cavalry. During World War I he served in France from December 1917 to May 1919 and was discharged as captain in the Air Service. He was a factory representative for asphalt roofing from 1920 to 1931.
Sutphin was elected as a Democrat to the Seventy-second Congress and to the five succeeding Congresses (March 4, 1931–January 3, 1943). He was an unsuccessful candidate for reelection in 1942 to the Seventy-eighth Congress.
After leaving office, he went on to be vice president of the M.J. Merkin Paint Co., in New York City. He retired in 1951 and resided in Berlin, Maryland. Sutphin died in Salisbury, Maryland on October 14, 1972 and was interred in Arlington National Cemetery.