Page "Marxism–Leninism" Paragraph 41

From 1925 to 1927, Stalin abandoned his triumvirate with Kamenev and Zinoviev and formed an alliance with the most right-wing elements of the party, Nikolai Bukharin, Alexei Rykov, and Mikhail Tomsky.

The 1927 Party Conference gave official endorsement to the policy of Socialism in One Country, while Trotsky along with Kamenev and Zinoviev ( both now allied with Trotsky against Stalin ) were expelled from the Party's Politburo.