The Bolshevik Revolution or the October Revolution overthrew the provisional government and established the Soviet Union.
It only took six months for the Bolsheviks to prepare this. Upon realizing that, it is difficult to maintain power in an election based system without sharing power with the other parties, the Bolsheviks decided to abandon the democratic process in January 1918.
They then declared dictatorship rule which was the reason for the Russian Civil War which lasted till 1920.