In 1992, Coppersmith won the Democratic primary in Arizona's 1st District and faced three-term RepublicanJay Rhodes in the general election. On paper, Coppersmith faced extremely long odds. This East Valley-based district had been in Republican hands without interruption since 1953, and the Democrats had only made two serious bids for the seat since then. Rhodes had won the seat with over 70 percent of the vote each time, and no Democrat even filed against him in 1990. It had seemingly become even more Republican when most of its Hispanic residents were shifted to the 2nd District during redistricting. Also, popular Senator John McCain was running for re-election. Rhodes, however, was hobbled by ethics problems, and Coppersmith defeated him by just over six points in what was later called one of the biggest upsets in Arizona political history. While serving in Congress, he kept a campaign promise by returning a congressional pay raise he opposed by writing a check each month to the U.S. Treasury. Coppersmith also gained national attention with his leadership of the effort to eliminate the Advanced Liquid Metal Reactor program, an effort that united a coalition of budget-cutters, environmentalists, and foreign policy experts concerned about plutonium. Also, through his efforts, the U.S. Department of Labor and Department of Education talked with each other to end an interpretation of labor laws that kept parents in some Arizona schools from participating in their children's classrooms.
Senate race and private practice
In 1994, Coppersmith gave up his seat after only one term to run for the U.S. Senate when Dennis DeConcini retired. He lost to fellow CongressmanJon Kyl by 14 points. Proving just how Republican this district still was, no Democrat has come within 10 points of winning the district since Coppersmith left office. The district has since been renumbered as the 6th District, and is now the 5th District. After leaving Congress, Coppersmith spent two years as the chairman of the Arizona Democratic Party. He is an attorney specializing in real estate law and a managing partner of the law firm of Coppersmith Schermer & Brockelman PLC. He has a blog called . He is also a member of the ReFormers Caucus of Issue One.