Communist leader
After the killing of the KPD's main leaders Rosa Luxemburg, Karl Liebknecht, and Leo Jogiches, Levi took over as the central leader of the Communist Party. At the KPD's second congress in October 1919, Levi expelled the party's Council Communist ultra-left, around half the membership many of whom formed the Communist Workers' Party of Germany. During the Kapp Putsch Levi was in prison.
Levi headed the German delegation to the 2nd World Congress of the Communist International (Comintern) in Moscow in 1920, where he threatened that the KPD delegation would leave due to the presence of representatives of the KAPD.
He led the party away from the policy of immediate revolution, orientating it to wider layers of workers. These efforts were rewarded when a substantial section of the USPD joined the KPD after a debate at their Halle congress, making it a mass party for the first time with around 449,700 members. This was followed up by an 'Open Letter' which Levi, alongside Radek, convinced the KPD Zentrale to issue to other working class organisation to join in a joint struggle around their common interests, based on a successful initiative of Communists in Stuttgart.
Levi attended the 1921 Livorno Congress of the Italian Socialist Party (PSI) which had joined the Comintern, where Levi had supported Giacinto Serrati against the faction around Antonio Gramsci and Amadeo Bordiga who went on to form the Italian Communist Party (PCI) supported by Comintern representatives Mátyás Rákosi and Khristo Kabakchiev. Following a debate at the Zentrale over Italy where Levi and his supporters lost the vote by a small majority after being opposed by Radek and Rákosi, he resigned from the chairmanship of the Communist Party in early 1921, alongside his co-chairman Ernst Däumig and Clara Zetkin, Otto Brass and Adolph Hoffmann also resigned from the Central Committee. This had been preceded by the "small bureau" of the Comintern condemning the "Open Letter" and awarding the KAPD sympathising section status. Shortly after, under the influence of Béla Kun, the party launched the March Action of 1921.
As leader of the KPD, Levi frequently criticized "putschism," or the repeated efforts on behalf of Communists to take power without the broader support of the masses. He first observed this phenomenon in the failed revolutionary experiences in Bavaria and Hungary in 1919. Later on, after the disastrous March Action, Levi wrote his most famous pamphlet Unser Weg: Wider den Putschismus ("Our Path: Against Putschism"). In it, he laid out his criticisms of the Comintern, the KPD, and what he called the "Bakuninist" influence behind what he argued were numerous premature attempts to take state power. Levi cited both Engels and Marx on insurrection, showing how other Party members of the KPD had overlooked the careful preparatory work of the Bolsheviks leading up to the October 1917 Revolution. He simultaneously criticized Comintern representatives such as Béla Kun, Grigory Zinoviev and Karl Radek for their encouragement of these accelerationist policies both in Germany and Italy. Levi's criticism of the Comintern and "putschism" served as an early attempt to explain the failure of European Revolutions in the 1918-1923 period.
Following the failure of the uprisings Levi was expelled from the Communist Party for publicly criticizing party policies in his pamphlet Unser Weg. Lenin and Trotsky substantially agreed with his criticisms, but not the way in which he had made them. Lenin sent him a private letter through his friend Clara Zetkin, in which he asked Levi to accept the expulsion for "breach of discipline" and then adopt a friendly approach towards the KPD and cooperate with it in the class struggle in a loyal manner. If Levi would do so, Lenin would then push for his reinstatement in the party. Levi did not accept this proposal and continued to criticize the party sharply and condemn its leaders. This led Lenin to revise his previously still favourable attitude towards Levi.
