The 1976 United States Senate election in New Mexico took place on November 2, 1976. Incumbent Democratic U.S. Senator Joseph Montoya ran for re-election to a third term, but was defeated by Republican Harrison Schmitt. As of , this is the last time that the Republicans have won the Class 1 Senate seat in New Mexico.
Harrison Schmitt's inauguration marked the first time since 1917 when both Senate seats were held by Republicans. Schmitt was the first non-Hispanic to have won this seat since Bronson Murray Cutting in 1934. This is also the last time a Democratic Senator from New Mexico lost re-election.
Schmitt won the election in a decisive victory. Joseph Montoya congratulated Schmitt on his victory, saying "The people have spoken and I accept their verdict."
In the pre-primary convention held on March 27, 1976, Schmitt received 73.7% of the votes and businessman Eugene Peirce received 21%, allowing both to qualify for the primary ballot. A third candidate, Arthur Lavine, received 5.3% of the votes, not enough to be placed on the primary ballot.
In the June 1 primary election, Schmitt defeated Peirce and became the Republican nominee.
Schmitt campaigned for 14 months, running a forward-looking campaign critical of Montoya's ethical issues. His slogan was "Honesty for a change." On the campaign trail, Schmitt, who was twenty years younger than Montoya, frequently said, "I have time for the future; Senator Montoya does not."
On the campaign trail in October, Senator Montoya repeatedly ridiculed Schmitt's experience as an astronaut by comparing him to a little monkey ("changito"), who could be trained to travel in space.