Tumulty served in the New Jersey General Assembly from 1944–1952, serving as minority leader in 1951. He was assistant corporation counsel for Jersey City from 1943–1954, was a delegate to the 1952 Democratic National Convention, and was secretary to the mayor of Jersey City in 1952 and 1953. Famous as a storyteller and also for his 300-pound frame, Tumulty described his time in the army as "I went in as a private and came out as a platoon."