Hall became active in politics, joining the Democratic Party in a change from his father's affiliation. He was elected as a member of the Ohio House of Representatives, serving from 1969 to 1973, and as an Ohio state senator from 1973 to 1979. In 1974, Hall ran for Ohio Secretary of State and lost to Republican incumbent Ted W. Brown.
U.S. Representative
Hall was first elected to the U.S. House of Representatives in 1978, to succeed 12-year incumbent Charles W. Whalen Jr., a moderate Republican. He won election with 54 percent of the vote, but would never face another contest anywhere near that close. He would be reelected 11 more times, never dropping below 57 percent of the vote. As a measure of how popular he was in the Dayton area, he was unopposed for reelection in 1984 even as Ronald Reagan carried the district in a landslide. He was unopposed again in 1990, and faced no major-party opposition in 1982 and 2000. In the 1980s, Hall became an evangelical Christian, prompting him to change his position on abortion from abortion rights to pro-life. Otherwise, his voting record was decidedly liberal. During his tenure in Congress, Hall concentrated on seeking to alleviate world hunger. He made frequent trips to more than 100 countries such as Sierra Leone, Ethiopia, Sudan, and North Korea where hunger was widespread. He was chairman of the Select Committee on Hunger from 1989 to 1993. When the committee was abolished, Hall fasted for 22 days in protest. He was founder of the Congressional Friends of Human Rights Monitors and the Congressional Hunger Center. Hall served terms on the foreign affairs and small business committees before being appointed to the House Rules Committee in 1981. Twice during his tenure as U.S. representative, Hall introduced legislation that would have apologized for slavery in the United States. Hall was an Ohio delegate to the 2000 Democratic National Convention.
With Tom Price, Hall wrote Changing the Face of Hunger: One Man's Story of How Liberals, Conservatives, Democrats, Republicans, and People of Faith Are Joining Forces to Help the Hungry, the Poor, and the Oppressed. In March 2007, Hall announced he was committed to fostering a Middle East peace initiative, by working with the Center for the Study of the Presidency and religious leaders of the Holy Land, principally among Muslims, Christians and Jews in the Middle East. Under a $1 million grant from U.S. Secretary of State Condoleezza Rice via the U.S. Agency for International Development, to be applied to both economics and faith-based efforts, Hall was to work with religious leaders to help prepare the way for peace in the Middle East. Hall received no salary for his work. He serves as the Director for The Alliance to End Hunger. Hall also serves on the Board of Advisors of Opportunity International, a charity that seeks to end poverty through microcredit lending to entrepreneurs.
Personal life
Hall and his wife, Janet Sue Dick, were married in 1973. They had two children together, Jyl Hall Smith and Matthew Hall. Matthew died in 1996, at age 15, of leukemia.