Benjamin served in the 95th, 96th, and 97th Congresses from 1977 until his death in 1982. Benjamin sat on the House Appropriations Committee, and served as the chairman of the House Appropriations Subcommittee on Transportation, aiding Northwest Indiana with projects such as improved Amtrak facilities, new South Shore Railroad commuter cars, and funding for an I-94 interchange to provide access to the Indiana Dunes National Lakeshore as well as improvements in Gary's bus system and municipal airport. In addition, Benjamin chaired the executive committee of the Congressional Steel Caucus, a bi-partisan coalition of congressman that promotes the health and stability of the domestic steel industry. To encourage the Calumet Region's economic recovery, Benjamin worked to establish the Calumet Forum, with representatives of labor, industry, banking, publishing, education, politics, transportation, and the religious community seeking to promote the economic resurgence and development of the Region. Regarding the importance of the Forum, Benjamin commented, "I've put myself on the line for this ... I've got to do it. It just has to be done."