Before serving in the U.S. Senate, Coats was a member of the United States House of Representatives, representing Indiana's 4th congressional district from 1981 to 1989. He was appointed to fill the Senate seat vacated by Dan Quayle following Quayle's election as Vice President of the United States in 1988. Coats won the 1990 special election to serve the remainder of Quayle's unexpired term, as well as the 1992 election for a full six-year term.