As the division between Bolsheviks and Mensheviks hardened, the Bund was increasingly drawn to the Menshevik side. The Mensheviks reversed their position on organisational federalism, making it possible for the Bund to rejoin the Menshevik wing of the RSDRP. In 1906, Liber represented the Bund at the 4th, Unification, Congress of the RSDLP in Stockholm when the Bund rejoined the party. At the 5th Congress in London in 1907 he was elected to the RSDLP Central Committee. During the abortive Revolution of 1905, Liber played a role as a Bundist representative in the soviets, even though he, like most SDs (including Lenin), initially greeted the new, spontaneous workers' organisation with some scepticism. When the Revolution petered out in 1907 and the autocracy reasserted its authority, Liber was one of those who advocated a more cautious, legalistic course of action for the RSDRP. Known as 'Liquidators' because they wanted to 'liquidate' the illegal underground organisation of the party, this group was fiercely opposed by Lenin as well as by 'Party Mensheviks' like Martov and Trotsky (then a Menshevik). However, Social-Democratic 'Liquidators' like Liber had counterparts among the Socialist-Revolutionaries, including Liber's contemporary A.R. Gots. Liber's subsequent close alignment with Gots in 1917 may have had its roots in their common 'Liquidationism' of the 1910s. During this period, Liber married, which may also have encouraged his emphasis on legal work.