Final answer:
Henry A. Wallace ran against Harry Truman in the 1948 United States presidential election as the Progressive Party candidate. The Progressive Party emerged as a faction of Democrats dissatisfied with Truman's conservative policies and Wallace's platform calling for an end to segregation and the Cold War, as well as pushing for universal health insurance.
Step-by-step explanation:
The candidate who ran against Harry Truman in the 1948 presidential election on the Progressive Party ticket was Henry A. Wallace. The Progressive Party was made up of Democrats who found Truman's policies too conservative. They were advocating for significant changes, including an end to segregation, equal rights for African Americans, a conclusion to the Cold War, and the establishment of universal health insurance.
Henry Wallace had served as a vice president under Franklin Roosevelt and was vocal about his progressive views, which set him apart from the mainstream Democratic Party. Despite the backing of the Progressive Party and their bold platform, Wallace and the party did not manage to win the presidency in 1948. The election saw a splintering of the Democratic Party, as Southern Democrats, known as Dixiecrats, also broke away, nominating Strom Thurmond on a pro-segregation platform. Nevertheless, Truman secured his re-election through a well-fought campaign.