The Communist Party of the Soviet Union was limited.
The Communist Party of Ukraine ( Комуністична Партія України Komunistychna Partiya Ukrayiny , КПУ , KPU ; Коммунистическая партия Украины ) , known as the Communist Party ( Bolshevik ) of Ukraine until 1952 , was the Ukrainian branch of the Communist Party of the Soviet Union ( CPSU ) . The Communist Party of the Soviet Union , abbreviated in English as CPSU , was the founding and ruling political party of the Union of Soviet Socialist Republics ( USSR or Soviet Union ) . The CPSU was the sole governing party of the Soviet Union until 1990 , when the Congress of People 's Deputies modified the article of the constitution , which had granted the CPSU a monopoly over the political system .