Michael Newbold "Mike" Castle (born July 2, 1939) is an American politician who was Governor of Delaware from 1985 to 1992 and the U.S. Representative for Delaware's at-large congressional district from 1993 until 2011. He is a member of the Republican Party.The district includes the entire state of Delaware and is the oldest intact surviving district in the nation. He was the longest-serving U.S. Representative in the state's history.