Popescu served as the Minister of Internal Affairs in the Gigurtu cabinet from July 4 to September 4, 1940, and in the First Antonescu cabinet from September 4 to September 14, 1940. In early July he helped manage the flow of refugees from Bessarabia and Northern Bukovina in the wake of the Soviet annexation of those Romanian territories. On August 30, Popescu participated in a meeting of King Carol II's Crown Council, where he was (alongside Gheorghe Mihail, Nicolae Păiș, and ) one of the four out of five military representatives who recommended accepting the provisions of the Second Vienna Award, by which Romania were to cede Northern Transylvania to Hungary.