He was the director of the Finance and Grants Management Division of the United States Office of Economic Opportunity from 1970 to 1973, and director of the Office of Property Management, Office of Federal Management Policy, United States General Services Administration from 1973 to 1975. He served as operations director for the United States House of Representatives Subcommittee on Oversight and Investigations, Committee on Interstate and Foreign Commerce from 1975 to 1979.
He was elected in 1980 as a Republican to the 97th United States Congress but was an unsuccessful candidate for reelection in 1982. After his term in Congress he became the Deputy Secretary of Revenue of the Commonwealth of Pennsylvania, from 1983 to 1985.
In 1991, Nelligan ran for a seat on the Luzerne County Board of Commissioners, running on a ticket with incumbent commissioner James Phillips. While Phillips won reelection, Nelligan ultimately lost the election.[1]
On February 18, 2014, his wife, the former Jean Kessler, died from injuries sustained in a serious car crash that occurred on February 17, 2014.[2]