Bolshevism (derived from Bolshevik) is a revolutionary socialist current of Soviet Leninist and later Marxist–Leninist political thought and political regime associated with the formation of a rigidly centralized, cohesive and disciplined party of social revolution, focused on overthrowing the existing capitalist state system, seizing power and establishing the "dictatorship of the proletariat". Bolshevism originated at the beginning of the 20th century in Russia and was associated with the activities of the Bolshevik faction within the Russian Social Democratic Labour Party, led by Vladimir Lenin. Remaining on the soil of Marxism, Bolshevism at the same time absorbed elements of the ideology and practice of the revolutionaries of the second half of the 19th century (Sergey Nechaev, Pyotr Tkachev, Nikolay Chernyshevsky) and had many points of contact with such domestic left-wing radical movements as populism. The main theorist of Bolshevism was Vladimir Lenin; besides him, the theoreticians of Bolshevism include Leon Trotsky, Nikolai Bukharin and Yevgeni Preobrazhensky. In October 1917, the Bolshevik Party won a majority in the revolutionary workers' councils (soviets) which had been formed throughout Russia following the February Revolution. It subsequently organized the October Revolution, which overthrew the Provisional Government and replaced it with a state power under the control of the soviets, led by the Bolsheviks along with other left-wing socialists. Some researchers attribute to Bolshevik theory the program of Joseph Stalin, who headed the All–Union Communist Party (Bolsheviks) and at the same time possessed full state power in the Soviet Union. However, others (both Stalin's contemporaries and later) do not confuse "Bolshevism" and "Stalinism" proper, considering them to be multidirectional (revolutionary and thermidorian) phenomena. The expression "Bolshevism", as well as "communism" later, has become established in Western historiography in the sense of a certain set of features of Soviet power in a certain political period.