Well, both the Soviet occupation forces and the Romanian Communist Party (PCR) forced King Michael I to abdicate in December 1947 and formally ended the monarchy. So Romania was not really a communist monarchy; King Michael I presided over a shifting political landscape in the wake of the August 1944 coup that deposed the German-allied Ion Antonescu. The Soviets stomached Michael I's presence in Romania but they did not relish it either. The period between 1944 and Michael I's exile in January 1948 saw a gradually diminished role for the monarchy.

Although the PCR's propaganda and official history liked to claim that it played a leading role in the 1944 coup, the reality was that the PCR was not a unified entity and split between so-called home communists and Moscow-based communists. The former were represented primarily by Gheorghe Gheorghiu-Dej, an activist who spent a good deal of time in prison during Antonescu's reign. The Soviets preferred to work with those communist they had more firmly under their thumb, ie those individuals who were emigres within the USSR. This was of a piece with the wider approach of the USSR to communist parties and leaders. The Soviet occupation in Germany placed far greater support to Moscow-based KPD leaders rather than those who escaped fascism in the West or spent their time in German jails. But Dej and his faction had the benefit of timing. The Soviet drive to liberate the remaining bits of Soviet territory controlled by the Germans and defeat Hitler meant that they subordinated ideological control to the immediate needs of the front. This was partly why the Soviets were also amenable to Michael I's coup and ability to appoint a PM. A flexible approach eliminated Romania as part of the Axis coalition, put German forces in SE Europe at a disadvantage, and ensured that the central drive to Poland and Germany could take place with minimal distractions.

Soviet diplomacy with the Western allies also played a role in the ultimately temporary accommodation with the monarchy. Churchill had agreed to the Soviets having a 90% control of Romania. What 90% meant in reality was hard to say, but it did mean that Stalin could not abolish the monarchy by fiat. The Soviet occupation had to work within certain existing boundaries of the Armistice of September 1944. The process of Sovietization, which entailed strengthening the PCR, tentative steps to collectivizing agriculture and industry, and securing Romania as a bulwark of Soviet power began under the occupation, but not without their frictions. Both the British and the American representatives to Romania tended to look to the King as a firewall against the Sovietization of the country. Michael I was also generally opposed to Sovietization of Romania and made allies with the Peasant Party's Iuliu Maniu. One sign of the relative independence of Michael I was his appointment of General Nicolae Radescu as PM in December 1944. Radescu was critical of both the German alliance and Antonescu's dictatorship, but he was also relatively anti-communist in his politics. Moscow did not like Radescu's appointment and neither did the PCR. If Radescu'a appointment showed the latitude of Michael I's powers, the forced resignation of Radescu in March 1945 and replacement by Petru Groza, one of the heads of the Plowman's Front, one of the subsidiary parties aligned with the PCR, showed the monarchy's limits. Groza's appointment increased the Sovietization of the country and strengthened the hand of the PCR in national politics.

While Stalin occasionally showed signs of being willing to work with Michael I for a postwar Romania, the reality was Soviet policy was geared towards eliminating the monarchy. The logic of Soviet occupation was that the end result of any government was that it would be dominated by reliable members of local communist parties. This logic did not always proceed in an iron-clad trajectory. The initial years of Soviet occupation in Europe witnessed a resurrection of a Popular Front approach to politics in which communist parties would lead coalitions among left-wing socialist and peasant parties. Nor did the Soviets necessarily know whom they were to designate as their lieutenants in Eastern Europe. Dej's success in securing a place in postwar Romania was in no small measure due to his own activities in sidelining emigre rivals who had closer connections with Moscow and making his deputies in the PCR preeminent in the postwar party. Bracketed as it was between a Soviet occupation that saw the monarchy as a means to an end on the best of days and communist factions vying for control, the Romanian monarchy was on borrowed time after V-E Day.

Sources

Békés, Csaba, László Borhi, Peter Ruggenthaler, and Ottmar Trașcă. Soviet Occupation of Romania, Hungary and Austria, 1944/45-1948/49. New York: CEU Press, 2015.

Deletant, Dennis. "New Light on Gheorghiu-Dej's Struggle for Dominance in the Romanian Communist Party, 1944-49." The Slavonic and East European Review 73, no. 4 (1995): 659-690.

Roper, Stephen D. Romania: The Unfinished Revolution. London: Routledge, 2000.