McCarthy was a resident of St. Paul, former high school teacher and college professor, and sitting U.S. Representative (CD 04, 1949-1959).
Petersen was an editor and publisher from Askov, a former state Representative (HD 56, 1931-1935), Lieutenant Governor (1935-1936), and Governor (1936-1937), sitting Railroad and Warehouse Commissioner (1937-1943, 1955-1967), Farmer-Labor candidate for Governor in 1938, Farmer-Labor nominee for Governor in 1940 and 1942, Republican candidate for Governor in 1946, and DFL candidate for Governor in 1950.
Miller was a resident of Anoka and DFL candidate for the 3rd CD in 1966 and 1968.