From 1976 to 1980, Coats worked for then-U.S. Representative Dan Quayle, a Republican from Indiana's 4th congressional district, as Quayle's district representative. When Quayle decided to challenge three-term Democratic incumbent Birch Bayh in the 1980 U.S. Senate election, Coats ran for and won Quayle's seat in the U.S. House.