John J. “Jack” Cochran

John J. “Jack” Cochran was a Missouri congressman and one of Harry S. Truman’s two principal opponents in the 1934 Democratic primary for the United States Senate. Experienced in Washington and initially favored to win, Cochran combined a substantial political reputation with a campaign effort to keep the contest focused on the public’s urgent economic hardships. His defeat was decisive: Truman won the primary by more than 40,000 votes, with the result in Jackson County overwhelming Cochran’s advantage in St. Louis.

Identity and Political Standing

Cochran represented St. Louis in Congress and was described as a large, friendly, humorous, and honest man. He was regarded as a congressman’s congressman, familiar with the intricacies of government, and his experience made him far better known than Truman. Before the primary, Cochran was considered the likely winner. His reputation and Washington experience gave him an apparent advantage over Truman, a county judge whose most conspicuous political strength was his connection to the Pendergast political machine.

Cochran also had organized support in his home region. The St. Louis organization associated with the city’s political machine backed him, while Senator Bennett Clark supported the other challenger, Jacob L. “Tuck” Milligan. Clark’s support for Milligan was seen as part of his effort to challenge Tom Pendergast and secure a second Senate seat for himself. Cochran therefore entered a race shaped not only by the candidates’ individual records but by competing political organizations and their reach across Missouri.

Campaign and the Machine Issue

Cochran and Milligan began campaigning weeks before Truman. Both made Truman’s association with the Pendergast organization the central vulnerability in his candidacy, portraying him as a machine’s dependent rather than an independent contender. Their attacks gained force when excesses connected with the organization returned to the headlines: violence during municipal elections in Kansas City left dozens injured and four people dead. In that atmosphere, Cochran and Milligan could present Truman’s political backing as a liability, not simply an advantage.

Truman answered the machine charge at a statewide rally in Columbia, where his speech was broadcast by radio. He reminded listeners that Cochran and Milligan had themselves sought and received the Kansas City organization’s endorsement when they ran for congressman at large two years earlier. The retort complicated the opponents’ effort to cast Truman alone as beholden to machine politics: their own earlier campaigns, he argued, had also sought its support. Cochran’s position was especially exposed to this counterargument because he, too, had benefited from political organization and endorsements, even as he challenged the power behind Truman.

As the campaign continued, Truman tried to shift attention from political maneuvering to the Depression. The contest unfolded amid falling farm prices, foreclosures, drought, and the visible hardship of rural families. Cochran, for his part, objected to turning the election into a mudslinging contest. He argued that personal attacks were a luxury in prosperous times and had no place when so many people were suffering. His intervention marked a contrast in tone: even in a bitter primary, he called for attention to the crisis facing voters rather than further escalation of accusations.

Primary Result

By the final stretch, Milligan was clearly falling behind, while Cochran and Truman appeared to be running neck and neck. On August 7, 1934, Truman won with 276,850 votes to Cochran’s 236,105; Milligan finished third with 147,614. Truman’s margin over Cochran was 40,745 votes. The result overturned the early expectation that the better-known congressman would prevail.

The geography of the vote helps explain the outcome. Truman did well among farmers, but Cochran also carried as many counties as he did. The decisive difference was Jackson County, where Truman received 137,000 votes—nearly half his statewide total. Cochran and Milligan together received only 11,000 votes there, despite Cochran having carried the county by 95,000 votes in his earlier congressional race, when he had Pendergast support. In some Kansas City precincts, Cochran received no votes at all. The organization that had seemed to make Truman vulnerable instead supplied the overwhelming local margin that carried him to victory.

Cochran later identified his prediction that he would receive 125,000 votes in St. Louis as a major mistake, believing it had spurred the Pendergast organization to work harder. His actual margin in St. Louis and St. Louis County was 112,000 votes, short of the 125,000 he had forecast. That regional strength could not compensate for Truman’s Jackson County landslide. Cochran’s defeat thus exposed the limits of his apparent advantages: name recognition, congressional experience, and a strong home base did not outweigh Truman’s command of the county where the machine’s influence was greatest.