How did Stalin gain complete control

During the second half of the 1920s, Joseph Stalin set the stage for gaining absolute power by employing police repression against opposition elements within the Communist Party. The machinery of coercion had previously been used only against opponents of Bolshevism, not against party members themselves. The first victims were Politburo members Leon Trotskii, Grigorii Zinov'ev, and Lev Kamenev, who were defeated and expelled from the party in late 1927. Stalin then turned against Nikolai Bukharin, who was denounced as a "right opposition," for opposing his policy of forced collectivization and rapid industrialization at the expense of the peasantry.