Smith served on the Somerset Township board of trustees, 1962 to 1968. He was township supervisor and on the Hillsdale County board of supervisors from 1966 to 1968. He then served as assistant deputy administrator and director of energy in the United States Department of Agriculture between 1972 and 1974.
Smith ran for Congress in the 7th District in 1992, winning the Republican primary by seven points. His nearest opponent was fellow state senator Joe Schwarz, a considerably more moderate Republican. Smith was the major candidate from the eastern portion of the district, while Schwarz and the others were all from the western portion. The candidates from the western portion split the vote, allowing Smith to win despite getting only 37 percent of the vote. No Democrat even filed for the general election, handing the seat to Smith. He was reelected five times.
Smith was a relatively low-profile congressman for most of his career, compiling a reliably conservative voting record despite representing a fairly marginal district. However, Smith gained national attention in 2004 in the controversy over the Medicare Modernization Act. Smith had announced earlier he was not running for reelection later that year, having promised during his initial run to only serve six terms (12 years) in the House. However, he'd endorsed his son, Brad, as his successor. Smith stated that members of the House Republican leadership told him that if he voted for the Medicare bill, business interests would give $100,000 to his son's campaign. When Nick Smith refused to vote for the bill, he was told that his son would never get into Congress. Ultimately, Brad Smith was defeated in the Republican primary by Schwarz, who was elected in November.
