[1] When the PSR split he sided with the Party of Left Socialist-Revolutionaries (internationalist), and became a member of the Ufa Governorate Committee of the PLSR(i).
[1][4] In early 1918, Maksimov went to Petrograd to attend the Third All-Russian Peasants Congress as a representative of the PLSR(i) from Ufa.
[5][6] During the 6 July 1918 Left SR uprising, Maksimov was one of the members of the PLSR(i) faction at the Fifth All–Russian Congress of Soviets and was arrested at the Bolshoi Theatre during the crackdown of the revolt.
[1] Whilst underground he was informed that he had been elected in absentia to the Central Committee of the Party of Revolutionary Communism.
[1] In 1919, Maksimov was part of the effort to unite the Party of Revolutionary Communism with other populist factions, on a platform of support of soviet power.
[8] Subsequently the Central Committee majority decided to expel Evgenia Semenovskaya, Vladimir Zitta, Vladimir Bezel and Maksimov from the party for 'violation of party discipline' and for seeking unity with populist sectors (including groups such as the PLSR(i) or the PSR).
[9][8] After being expelled from the Party of Revolutionary Communism, Maksimov's mandate in the All-Russian Central Executive Committee was declared invalid.