|Elections in Wisconsin|
The 1940 United States Senate election in Wisconsin was held on November 5, 1940.
Incumbent Progressive U.S. Senator Robert La Follette Jr. was elected to a third term in office over Republican Fred H. Clausen and Democrat James E. Finnegan.
|Progressive||Robert M. La Follette Jr. (incumbent)||144,692||100.00%|
Frank died two days before the primary, on September 15, but remained on the ballot.
|Republican||Fred H. Clausen||109,293||31.23%|
|Republican||John P. Koehler||64,774||18.51%|
|Republican||Glenn Frank (deceased)||47,885||13.68%|
|Republican||Michael G. Eberlein||43,784||12.51%|
|Republican||William C. Maas||29,940||8.56%|
|Republican||Reuben W. Peterson||29,331||8.38%|
|Republican||Walter B. Chilsen||24,928||7.12%|
|Democratic||James E. Finnegan||55.145||42.79%|
|Democratic||William D. Carroll||36,306||28.17%|
|Democratic||James J. Kerwin||22,642||17.57%|
|Democratic||John Cudahy (write-in)||14,773||11.46%|
|Progressive||Robert M. La Follette Jr. (incumbent)||805,609||45.26%||2.52|
|Republican||Fred H. Clausen||553,692||41.38%||18.54|
|Democratic||James E. Finnegan||176,688||13.20%||11.04|
|Socialist Labor||Adolf Wiggert||838||0.06%||N/A|