In October 1917 two soviet meetings were held: Soldiers' and Workers'soviets and Farmers'soviets. In the former Bolsheviks had 338/739 seats. These soviets represented only about 20% of population. 80% were represented by the farmers' soviets. But, according to wiki, these soviets took the power. For better outlook, some deputies from the farmers' soviets were imported. Notice, even in these soviets, bolsheviks did not have majority. (They never won any votes honestly).
Simply in 1917-8 all other parties, starting from cadets and right esers, and ending by left esers and maximalists/anarchists, were declared outlaws. And finally only bolsheviks remained.
Recursively, more left parties helped bolsheviks to dispose of the right ones, only to be disposed, too, at the next turn. The last liquidated political ally were anarchists - they were not already in soviets, but they were allies in the battle against Crimea. Simply at some moment bolsheviks turned they weapons at 90% degrees and destroyed the "allies".
What is the most interesting, when I visited one antifascist demonstration in Prague in 1997, I found that nowadays anarchists again play allies of communists. The explanation sounded as: "communists are different now".