Announcement of the Marshall Plan, expulsion of communists from the French and Italian governments in 1947, and consolidation of the Western bloc unnerved Stalin. Anticommunist forces, though in disarray, still lurked in Eastern Europe most of the region's communist governments and parties enjoyed meager popular support and the Polish, Czechoslovakian, Bulgarian, and Yugoslav communist parties began pursuing independent lines regarding acceptance of Marshall Plan aid and formation of a Balkan confederation. Fearing the Soviet Union might lose its grasp on Eastern Europe, Stalin abandoned his advocacy of "national roads to socialism" and pushed for establishment of full communist control in Eastern Europe with strict adherence to Moscow's line. To further this goal, in September 1947 the Soviet Union and its satellites founded the Cominform, an organization linking the Communist Party of the Soviet Union (CPSU) and the communist parties of Eastern Europe, Italy, and France.

In the second half of 1947, the Romanian Communists unleashed full fury against the country's other political parties, arresting numerous opposition politicians and driving others into exile. The government dissolved the National Peasant Party and National Liberal Party, and in October prosecutors brought Iuliu Maniu, his deputy, Ion Mihalache, and other political figures to trial for allegedly conspiring to overthrow the government. Maniu and Mihalache received life sentences in 1956 the government reported that Maniu had died in prison four years earlier. In late 1947, the Communists struck against their fellow travelers, ousting the opportunistic members of the main opposition parties who had cooperated in the Communists' takeover. A terror campaign claimed many lives and filled prisons and work camps. After ridding themselves of all active political opponents, Groza and Gheorghiu-Dej met with King Michael in December 1947 and threatened him with a government strike and possible civil war unless he abdicated. After several refusals, the king submitted.

The Romanian Communist Party and one wing of the Social Democratic Party merged in early 1948 to form the Romanian Workers' Party (Partidul Muncitoresc Romān--PMR). Communists held the party's key leadership posts and used the principle of democratic centralism to silence former Social Democrats. The PMR's First Party Congress, in February 1948, chose the triumvirate of Gheorghiu-Dej, Luca, and Pauker to head the Central Committee Gheorghiu-Dej remained general secretary but still lacked the power to dominate the others. The Congress also transformed the National Democratic Front into the Popular Democratic Front, the party's umbrella front organization. In the same month, the Soviet Union and Romania signed a treaty of friendship, cooperation, and mutual assistance.

Data as of July 1989