Dayton ran for the U.S. Senate in 1982 against Republican Party incumbent David Durenberger. He defeated former U.S. Senator Eugene McCarthy in the Democratic primary, and the general election became one of the most expensive in state history. Dayton campaigned as a populist in opposition to Reaganomics and famously promised "to close tax loopholes for the rich and the corporations and if you think that includes the Daytons, you're right". Durenberger won the election, and Dayton returned to the Perpich administration until his election as Minnesota State Auditor in 1990.