The 1964 United States Senate election in Wisconsin was held on November 3, 1964. Incumbent Democrat William Proxmire was re-elected to a second term in office over Republican Wilbur Renk.
Democratic primary
Candidates
Kenneth F. Klinkert
William Proxmire, incumbent Senator since 1957 (Democratic) Arlyn F. Wollenburg
Results
After losing the primary, Klinkert entered the general election as a candidate running on a "Faith and Belief in Man" ticket.
Republican primary
Candidates
Wilbur N. Renk, candidate for Governor in 1962
Results
General election
Candidates
Wayne Leverenz (Socialist Workers) Kenneth F. Klinkert (Faith and Belief in Man) William Proxmire, incumbent Senator (Democratic) Wilbur N. Renk, candidate for Governor in 1962 (Republican)