Question: Which ideologies helped formalize the ideas of the third member of the triumvirate, along side Zinoviev and Kamenev,. 
Sentence (from "Left Opposition"): Originally, the battle lines were drawn between Trotsky and his supporters who signed The Declaration of 46 in October 1923, on the one hand, and a triumvirate (also known by its Russian name "troika") of Comintern chairman Grigory Zinoviev, Communist Party General Secretary Joseph Stalin and Politburo chairman Lev Kamenev on the other hand.
Relevant evidence: No