United States Senate election in Missouri, 1934
Truman: 40–50% 50–60% 60–70%
70–80% 80–90% >90%
Patterson: 40–50% 50–60% 60–70% 70–80%
The 1934 United States Senate election in Missouri was held on November 6, 1934. Incumbent Republican U.S. Senator Roscoe Patterson, first elected in 1928, sought reelection to a second term. He was defeated by the Democratic nominee, future President of the United States Harry Truman.
Harry Truman, having served as a judge, expressed an interest in running for the U.S. House of Representatives in 1934, but political boss Tom Pendergast had already selected another candidate for that race. After four other potential candidates had declined to run, Pendergast ultimately approached Truman to discuss a possible run for the United States Senate, to Truman's surprise. Truman, with backing from Pendergast, entered the Senate race. Truman said he would not, if elected, dictate to anyone, to the dismay of anti-Pendergast U.S. Senator Bennett Champ Clark.
Truman waged a statewide campaign and eventually won the largely three-way Democratic primary on August 7, 1934, by a significant margin, defeating U.S. Representatives John Cochran and Jacob Milligan.