Schumacher joined the SPD in 1918 and served as editor of its newsletter during 1920–1924. He was elected to the Württemberg Diet in 1924, serving until 1931, and to the Reichstag in 1930, serving until 1933. He was imprisoned much of the time during 1933–1944 because of his opposition to Nazi rule.
In 1945, Schumacher became a driving force in the recreation of the SPD, proving to be a staunch opponent of the merging of the party with the German Communist Party (KPD). The October 1946 merger agreement reached with Otto Grotewohl, chairman of the German Democratic Republic (GDR, East German) SPD, confirmed Schumacher's status as the leading SPD politician in Germany's western occupation zones. After the fusion of the SPD and KPD in the Soviet occupation zone, which brought the Socialist Unity Party (SED) into being, Schumacher was elected chairman of the SPD for West Germany and West Berlin. A member of the Parliamentary Council since 1948, he supported the founding of West Germany but repeatedly stressed its provisional character.
Schumacher's campaign to become the first West German president ended unsuccessfully in the September 1949 elections. As a member of the Bundestag (lower house of parliament) since 1949 and especially as opposition leader of the SPD group, he became one of the strongest critics of Chancellor Konrad Adenauer, whose policy of integrating West Germany into the Western bloc was regarded by Schumacher as the main obstacle to Germany's reunification. Schumacher called Adenauer "the chancellor of the Allies" during a parliamentary debate in November 1949 and was excluded from a subsequent session. Schumacher not only opposed the dismantling of Ruhr industry and the agreements on the Saar region but also fought against the entry of West Germany into the European Council and against the founding of the European Steel and Coal Community. In spring 1952, he regarded the so-called Stalin Note, a Soviet propaganda proposal to reunite Germany, as an important step forward, but Adenauer rejected Schumacher's demand to consider it seriously. Schumacher died in Bonn on 20 August 1952.
Childs, David. From Schumacher to Brandt: The Story of German Socialism, 1945–1965. Oxford and Frankfurt: Pergamon, 1966.; Edinger, Lewis J. Kurt Schumacher: A Study in Personality and Political Behavior. Stanford, CA: Stanford University Press, 1965.; Merseburger, Peter. Die schwierige Deutsche, Kurt Schumacher: Eine Biographie. Stuattgart: Deutsche Velags-Anstalt, 1995.; Moeller, Robert G., ed. West Germany under Construction: Politics, Society, and Culture in the Adenauer Era. Ann Arbor: University of Michigan Press, 1997.