The son of a Lutheran missionary, Mr. Simon disclosed his personal finances in the 1950s, long before it was fashionable, and sponsored the first open-meetings law in Illinois. His demeanor was so strait-laced that he earned the nickname "Reverend" while he serving in the Illinois legislature from 1955 until 1968.

Born Nov. 29, 1928, in Eugene, Ore., after his parents returned from missionary work in China, Mr. Simon enrolled in the University of Oregon to study journalism but transferred to Dana College in Blair, Neb., when his parents moved to southern Illinois. In 1948, he dropped out of college, borrowed $3,600 and bought a failing weekly newspaper in Troy, Ill., a town of about 1,500 near St. Louis. He became the nation's youngest editor-publisher at the time. He eventually built a chain of 14 weekly newspapers, which he sold in 1966.

For the next two years, Mr. Simon taught at Sangamon State University in Springfield, Ill., and at Harvard University's John F. Kennedy School of Government. He was elected to Congress in 1974 and represented a southern Illinois district for 10 years. In 1984, he took on three-term GOP Sen. Charles Percy, chairman of the Foreign Relations Committee, accusing Percy of personally benefiting from the Reagan tax cuts and casting him as the candidate of "country clubs and boardrooms." He won, 50 to 48 percent. Six years later, Mr. Simon faced a reelection challenge from Rep. Lynn Martin, a Republican. Mr. Simon won with 65 percent of the vote.