Chapman was elected in 1985 as a Democrat in the 99th Congress during a highly visible special election to fill the vacancy caused by the resignation of U.S. Representative Sam B. Hall. He defeated the Republican choice, Edd Hargett, a former professional football player, by just over 1,900 votes. However, he would never face another contest anywhere near that close, and was reelected to the five succeeding Congresses (August 3, 1985 – January 3, 1997). He was not a candidate for reelection to the One Hundred Fifth Congress in 1996, but was an unsuccessful candidate for nomination to the United States Senate in 1996.