The 1940 Missouri Democratic Senate Primary was a close contest that returned Harry S. Truman to the Senate despite corruption charges and the political damage associated with the collapse of the Pendergast organization. Truman’s victory over incumbent governor Lloyd C. Stark was decided by fewer than 8,000 votes out of 665,000 cast. The result showed that Truman retained a political base in Missouri even when his opponents tried to make his past association with Tom Pendergast the central question of the campaign.

A three-way contest

The primary initially appeared to favor Stark. Maurice Milligan, the district attorney who had prosecuted the Pendergast organization, entered the race believing that his role in bringing down Tom Pendergast entitled him to the Senate seat. Truman’s supporters later speculated that Milligan had been maneuvered into the contest to divide votes that might otherwise have gone to Stark. That claim was never substantiated, but Milligan’s presence did split the field, and his candidacy soon lost strength.

In the first weeks, Stark stood well ahead, Milligan followed, and Truman was a distant third. A cartoon in the St. Louis Post-Dispatch pictured the Stark and Milligan campaigns as heavy trucks colliding above a tiny Truman vehicle; its caption dismissed the smaller contender as having no place in the contest. As Milligan faded, the primary became a direct struggle between Stark and Truman. The contest’s changing shape mattered: the race that began as a test of Truman against two better-positioned candidates became a comparison between Stark’s attacks and Truman’s restraint.

Stark’s attacks and Truman’s restraint

Stark’s campaign quickly made Truman’s connection to Pendergast its target. Stark described him as a political lackey, a rubber-stamp senator, and a fraud, and accused him of having been elected through fraudulent votes. The charge gave Truman a chance to answer with a damaging document: his files contained a letter in which Stark had thanked him for introducing him to Pendergast. Campaign staff urged Truman to release it, convinced it could settle the contest at once. Truman refused, choosing not to expose the letter and instead expecting Stark’s own conduct to damage his standing.

Small details also began to undercut Stark’s presentation. Observers noted that his chauffeur had to salute him. Stark further complicated his position by going to the national convention in Chicago as an announced candidate both for the Senate and for the vice-presidential nomination. These episodes supplied contrasts with Truman’s approach, but the contest remained close; no single incident alone explains the outcome.

The last days and the vote

Bennett Clark, who had initially withheld his support, became a consequential ally in the final phase. In St. Louis, he called people across the state, continuing to work even after he was hospitalized. Clark also influenced Bob Hannegan, a St. Louis Democratic organizer who had been working for Stark. Two days before the primary, Hannegan switched sides and began campaigning energetically for Truman. Truman later regarded this late change as the campaign’s biggest break.

The shift in support was especially important in St. Louis, where a joint appearance by Truman and Alben Barkley drew only 300 people to a hall that could seat more than 3,000. The poor attendance did not foretell the final result. On election night, Stark initially led by 11,000 votes, and Truman was heard to believe he had lost. Bess Wallace Truman, answering a late-night call from campaign worker David Berenstein, first took the news as a cruel joke; Berenstein called again to tell her that Truman was carrying St. Louis.

The final count gave Truman a margin of just under 8,000 votes. In St. Louis, his advantage over Stark was 8,411 votes, a margin associated in the account with Clark’s intervention and Hannegan’s last-minute work. Truman also carried Jackson County by 20,000 votes. That was only a fraction of his earlier margin there, but it was politically significant: despite the scandal and the opposition of the Kansas City Star, he prevailed in the county where association with the Pendergasts was supposed to make a candidate unelectable. He also did better among farmers than in 1934, and the account notes that Black voters supported him.

Aftermath and political meaning

The result produced sharply different explanations from Truman’s opponents. Maurice Milligan congratulated Truman and promised to support him in the fall election. Stark, by contrast, privately attributed his defeat to the machine vote, Clark’s efforts, federal appointees and WPA workers, and the failure of his rural support to materialize during a severe drought. His account emphasized forces working against him; the returns also demonstrated that Truman could attract support beyond the organization’s remaining strength.

Truman’s response to Milligan’s subsequent request for reappointment as district attorney reflected a different consequence of their rivalry. Truman wrote to Franklin D. Roosevelt that fairness required Milligan to get his job back. Stark’s later prospects turned out differently. When Truman learned that Roosevelt was considering Stark for a position on the Labor Mediation Board, he acted to ensure Stark did not receive it. Stark withdrew from politics and never again held public office.

The primary therefore did more than choose a nominee. It tested whether Truman could survive a campaign in which his opponents tied him to a discredited political organization, and it exposed the limits of treating that association as a complete account of his support. The close result depended on local political work, a late organizational switch, and votes in St. Louis and Jackson County. Three days after the election, Democratic colleagues in the Senate greeted Truman with an unusually enthusiastic welcome, an immediate sign that the narrow Missouri victory had commanded national attention within his party.