From early on, Rădăceanu was a member of the Romanian Social Democratic Party (PSDR), one of its main ideologists and representatives in the Chamber of Deputies, as well as a regular contributor to the socialist journals Libertatea and Lumea Nouă.

[4] In late January 1933, the pro-democracy Rădăceanu had criticized the steps taken by King Carol II to institute a more authoritarian regime after the fall of Iuliu Maniu's PNȚ cabinet.

[9] His political adversaries alleged that, during the period, he was also benefiting from good relations with Nazi German officials present in Romania.

[10] In 1944, the August 23 royal coup overthrew Antonescu, taking Romania out of its alliance with the Axis Powers and into the Allied bloc and leading to the reestablishment of pluralism in political life.

Romania under Soviet occupation witnessed a growth in influence for the PCR, which sought to impose its domination on the left-wing portion of the political spectrum.

Rădăceanu and Ștefan Voitec stood out inside the PSDR as advocates of close collaboration with the communists:[11] in March 1946, a conflict erupted between those two and Titel Petrescu, splitting the party into respective wings.

[13] The party, which remained in the National Democratic Front created around the PCR, ran on a single platform with the latter in the November 1946 general election (carried by the bloc through widespread electoral fraud).