In 1974 Blouin ran for the U.S. House seat in the Second District being vacated by fellow Democrat John C. Culver, who was running for the U.S. Senate seat being vacated by Harold Hughes. Blouin defeated Republican Tom Riley, an attorney from Cedar Rapids, in the general election. Blouin became one of many freshman Democrats in the largest Democratic majority in the House since 1965-67, providing a mathematical two-thirds majority in that chamber. For the only time since 1857, Iowa's congressional delegation included only one Republican.