The UKP was an offshoot party of the Ukrainian Social Democratic Labour Party (SD's) created in January 1920 by former members of the Social-Democrats who prior to that were organized as the group of the independent Social-Democrats, USDLP independents.
In 1923 a faction within the UKP sponsored by the secret police (CHEKA) requested unification with the CPU.
The Comintern, de facto run by the Russian Bolsheviks, answered that the Ukrainian republic as a sovereign state within the USSR was already represented and that therefore UKP should dissolve and unite with CP(b)U.
Recent research has shown that on the eve of their dissolution their influence was rising in Kyiv and Katerynoslav provinces.
Some members joined the Bolshevik CP(b)U, including its leader Andryi Richytsky in order to have some influence on Ukrainian politics.