1964 United States Senate election in Montana

The 1964 United States Senate election in Montana took place on November 3, 1964. Incumbent United States Senator Mike Mansfield, who was first elected to the Senate in 1952 and was re-elected in 1958, ran for re-election. Mansfield won the Democratic primary in a landslide, and advanced to the general election, where he faced Alex Blewett, the Majority Leader of the Montana House of Representatives and the Republican nominee. Though Mansfield's margin was quite reduced from 1958, he still overwhelmingly defeated Blewett and won his third term in the Senate in a landslide.

Candidates

 * Mike Mansfield, incumbent United States Senator
 * Joseph P. Monaghan, former United States Congressman from Montana's 1st congressional district, 1936 independent candidate for the United States Senate

Candidates

 * Alex Blewett, Majority Leader of the Montana House of Representatives
 * Lyman Brewster, rancher
 * Antoinette F. Rosell, State Representative