alternatehistory.com

The death of Stalin in 1926 set off a succession crisis within the All-Union Communist party leadership. By 1926, the Left opposition which had composed of Zinoviev, Kamenev and Trotsky had already being defeated at the party center. The opposition's primary power bases: Leningrad and Moscow had being taken over by Stalinists like Molotov and Kirov. This left them relatively powerless, and a convenient scapegoat for the recent murder of the General Secretary. Accused of "moral complicity", all three leaders were expelled from the central committee in January 1927, having already being expelled from the Politburo earlier in October 1926. By November 1927, all three would be expelled from the Communist Party entirely. [1]

This did not end the struggle for control over the Communist party and the World Communist movement, but rather set the stage for a another confrontation. This time between the "Stalinist group" (recent arrivals promoted to high level politics by Stalin): like Sergei Kirov, Lazar Kaganovich, Vyacheslav Molotov, and Anastas Mikoyan against the older generation of leadership under old Bolsheviks Nikolai Bukharin, Alexei Rykov, Mikhail Tomsky and Grigori Sokolnikov.

- Sheila Fitzpatrick, A History of the Soviet Union (2003), Cambridge University Press.

[1] As per otl, in the 1920s Stalin was actually considered a moderate in dealing with defeated left opposition members. With right oppositionists calling for harsher punishments, there is no reason to expect the Zinoviev et el to be treated leniently at least politically had Stalin died.