The immediate postwar years were dominated by the Liberal Party of the Old Kingdom. The party instituted a series of land reforms, fostered increased industrialization, and sponsored a broadly democratic constitution in 1923, which made the new state a centralized constitutional monarchy. The Transylvanian Romanians, long accustomed to considerable autonomy and self-government under Hungarian rule, resented the imposition of central control, especially under the administration of officials from Bucharest. In protest, a new party, the National Peasant Party, was formed in 1926 by a fusion of the Transylvanian National Party with the Peasant Party in the Old Kingdom. Other parties were active during this early period, but all were overshadowed by the Liberal Party and the National Peasant Party. The Social Democratic Party had been organized at the beginning of the twentieth century but, lacking any sizable number of industrial workers, the socialist movement remained weak. After the Russian revolution, however, the radical left-wing elements of the Social Democratic Party seceded and formed the Romanian Communist Party in 1921. The Communists went underground after being banned in 1924 and were largely ineffective until after World War II. The death of King Ferdinand in 1927 and the elections of the following year brought significant changes in the Romanian government. Ferdinand's son, Carol II, was excluded from the succession because of his earlier renunciation of all claims to the throne to accept exile with his mistress, Magda Lupescu. A regency was therefore appointed to rule in the name of Carol's young son, Michael, and a new government led by Iuliu Maniu and the National Peasant Party was elected, thus ending the six-year tenure of the Liberals. Although Maniu's government instituted a series of reforms intended to improve general economic and social conditions, its efforts were largely offset by the adverse effects of the worldwide depression of the early 1930s. Also, early dissatisfaction with the regency resulted in the return of Carol II from exile and his assumption of the crown in late 1930. His agreement to sever relations with Magda Lupescu was not kept, however, and in protest Maniu resigned the premiership. In the unstable conditions that followed, King Carol II emerged as the chief political figure in the country, and his rule evolved into a royal dictatorship.