Of the 7 members of the first Bolshevik Politburo, 4 were Jewish.
Sources:
#112 Grigory Zinoviev
#113 Leon Trotsky
#114 Lev Kamanev
#118 Grigori Sokolnikov
"Was the Russian Revolution Jewish?" - The Jerusalem Post [Archive]
"Politburo of the Communist Party of the Soviet Union" - Wikipedia
"Putin: Jews Ruined Russia – But Now We're Pals, Eh?" - The Jewish Daily Forward
"Vladimir Lenin" - JewOrNotJew.com