The founding congress of the
Communist Party of Germany (KPD) took place in
Berlin over three days between 30 December 1918 and 1 January 1919. The core of the founding membership consisted of those who had hitherto been
Spartacus League members; Flieg was a party member and part of the leadership team from the outset. He worked closely with
Willi Münzenberg on the creation of the
Young Communist International ("Kommunistische Jugendinternationale" / KJI), serving as a member of its executive committee from its launch in 1919 till March 1922. He was re-elected several times before
Communists were excluded from the Landtag in 1933. The
Communist Party of the Soviet Union (CPSU) became increasingly polarised during the later 1920s between those who were supportive of
Stalin and those who dared to speculate that perhaps
Lenin's successor should have been
Leon Trotsky. The CPSU and the KPD were closely linked at various levels; party ruptures in Moscow often found powerful echoes among the comrades in Berlin. A major programme of expulsions was carried out in 1928 following the
Wittorf Affair, during which Flieg was one of party leader
Ernst Thälmann's only allies. Many of those expelled later established
an alternative party. Sources insist that through this period Flieg carried out his party functions with skill, loyalty and meticulous care, without regard to whether the party leadership might be considered too far to the left or too far to the right. Then, in May 1932 Flieg was relieved by the KPD of his party responsibilities, seen as having become too close to
Heinz Neumann, a close political comrade and a personal friend. In 1930/31 Neumann had become critical of Thälmann, and thereby also of Stalin, both of whom, he said, were underestimating the dangers presented by the rise of the
Nazi Party. In April 1932 Neumann was stripped of his party functions and summoned to
Moscow. Flieg was identified as a "member of the Neumann group" and his demotions, accompanied by the inevitable mutterings about
Trotskyite sympathies, followed a few weeks later. His membership of the politburo was reduced to "candidate membership". == In exile ==