In 1917, the Russian Socialist-Revolutionary Party split between those who supported the Provisional Government, established after the February Revolution, and those who supported the Bolsheviks who favoured a communist insurrection. Left Socialist Revolutionaries demanded:

• condemn the war as imperialist and immediately get out of it;
• to cease cooperation with the Socialist Revolutionary Party Provisional Government ;
• immediately resolve the land issue in accordance with the program of the party, gave the land to the peasants.

The majority stayed within the mainstream party but a minority who supported the Bolshevik path became known as Left Socialist Revolutionaries. Maria Spiridonova was a prominent leader of this group. They, in effect, split from the main party. The split had not been completed before the Russian Constituent Assembly elections, the first meaningful electoral test between the parties in the peasant soviets a few weeks after the Assembly elections showed the parties had roughly equal support in the peasantry.