The 1940 United States Senate election in Minnesota took place on November 5, 1940. Incumbent U.S. Senator Henrik Shipstead defected to the Republican Party of Minnesota from the Farmer–Labor Party of Minnesota, and defeated former Governor Elmer Benson of the Farmer–Labor Party and John E. Regan of the Minnesota Democratic Party to win a fourth term.
Democratic primary
Candidates
Declared
Louis Erickson
John E. O'Rourke, Former Minnesota State Representative from the 27th district (1935-1937) John E. Regan, 1932 Democratic gubernatorial nominee and former Minnesota State Representative from the 8th district (1931-1933) Joseph Wolf
Results
Farmer–Labor primary
Candidates
Declared
Elmer A. Benson, 24th Governor of Minnesota (1937-1939) and former U.S. Senator (1935-1936) George H. Lommen, Minnesota State Senator from the 61st district since 1927
Results
Republican primary
Candidates
Declared
Ben Andreen
Ray P. Chase, Former U.S. Representative (1933-1935) and 9th Minnesota State Auditor (1921-1931) Michael Ferch O. J. Hagen Asher Howard, Former Minnesota State Representative from the 34th district (1917-1923) Martin A. Nelson, 1934 and 1936 Republican gubernatorial nominee (unsuccessful) Henrik Shipstead, Incumbent U.S. Senator since 1923 Engelberth Zeiner