Ideologically, the PCR was committed to Marxism–Leninism, a fusion of the original ideas of German philosopher and economic theorist Karl Marx, and Lenin, was introduced in 1929 by Soviet leader Joseph Stalin, as the party's guiding ideology and would remain so through much of its existence. In 1947, the Communist Party absorbed the Romanian Social Democratic Party, while attracting various new members. In the early 1950s, the group around Gheorghe Gheorghiu-Dej, with support from Stalin, defeated all the other factions and achieved full control over the party and country. After 1953, the Party gradually theorized a "national path" to Communism. At the same time, however, the party delayed the time to join its Warsaw Pact brethren in de-Stalinization. The PCR's nationalist and national communist stance was continued under the leadership of Nicolae Ceaușescu. Following an episode of liberalization in the late 1960s, Ceaușescu again adopted a hard line, and imposed the "July Theses", re-Stalinizing the party's rule by intensifying the spreading of communist ideology in Romanian society and at the same time consolidating his grip on power whilst using the Party's authority to brew a persuasive personality cult. Over the years, the PCR massively increased in size, becoming entirely submitted to Ceaușescu's will. From the 1960s onward, it had a reputation for being far more independent of the Soviet Union than its brethren in the Warsaw Pact. However, at the same time it became the most hardline party in the Eastern Bloc, harming its relationship with even the Communist Party of the Soviet Union. It collapsed in 1989 in the wake of the Romanian Revolution.