context: 13 members of the Central Committee and Central Control Commission signed the “Statement”, which once again pointed to the bureaucratization of the party apparatus as the main cause of the crisis that gripped the party [17]. At the July and October plenary sessions of the Central Committee (1926), the united opposition was also defeated: the majority supported the ruling group, opposition leaders - Trotsky, Zinoviev and Kamenev - were removed from the Politburo. In the fall of 1927, the so-called "pre-congress discussion" took place in the party; however, the Central Committee’s opposition platform refused to publish (and most of the party members were unfamiliar with it); it was illegal to print and distribute, for which many opposition members were expelled from the party even before the congress [18] [19]. Oppositionists were often not allowed to party meetings, thus depriving them of the opportunity to defend their point of view [20]. In October 1927, the last members of the opposition were expelled from the Central Committee, and Trotsky, Zinoviev and Kamenev in November 1927 from the party.
question: Who was the leader of the "Left Opposition" of the political current within the RCP in Russia?
answers.text: Trotsky, Zinoviev and Kamenev