Archival evidence sheds new light on the Truman administration's 1951 investigation into the “China Lobby” and its links to McCarthyism. Truman's advisors suspected connections among illicit funding streams generated by Chiang Kai‐shek's Nationalist regime in Formosa, illegal lobbying by unregistered agents, and a barrage of anti‐Communist propaganda from activists connected to McCarthy and the “China Lobby.” The White House worried that by flooding America's public discourse with charges of treason, the alleged conspirators were destabilizing the nation's ability to engage in reasoned deliberation about foreign policy. However, the White House could not persuade any congressional committees to manage an investigation, so it instead ran an executive operation that produced tantalizing clues but no prosecutable conclusions. Rather than proving its suspicions, the investigation created confusion and sowed doubts about Truman's judgment. Analyzing the administration's investigation provides new insights into the confusions and contradictions besetting America's grappling with the early Cold War and offers lessons on how not to defend democracy in a time of crisis.