Complex sentence: It pleaded to the Petrograd workers to reject the leadership of the Bolsheviks, whilst also rejecting the parliamentary factions (Mensheviks, Cadets, SRs, etc.).
Split into simpler sentences: It pleaded to the Petrograd workers to reject the leadership of the Bolsheviks. However, it also rejected the parliamentary factions (Mensheviks, Cadets, SRs, etc.).