A member of the Republican Party, Smith previously served in the Illinois state house from 1955 through 1969, including two years as Speaker of the House of Representatives from 1967 to 1969, prior to his appointment to the senate by governor Richard Ogilvie.

[1][2] Shortly after the start of World War II, Smith enlisted in the United States Navy Reserve, and commissioned an Ensign.

After a period of minesweeping in Okinawa, Smith was released into inactive duty as a Lieutenant.

[1][2] After his active navy service, he moved to Alton, Illinois and resumed the practice of law.

Upon the death of Everett Dirksen, Governor Richard B. Ogilvie appointed Smith to fill the vacancy in the United States Senate.