In April 1918, he entered the Alexandru Averescu-led People's League upon its establishment in Iași; in 1920, this would become the People's Party (PP), for a while the main opposition force to the PNL. Its mission, according to Negulescu, was to give legal expression to the revolutionary anti-PNL grievances. In November 1918, right after the Armistice with Germany and at the height of European revolutions, Negulescu's Bucharest home hosted negotiations between the radicalized PP and the Socialist Party of Romania (PS), during which it was proposed to turn Romania into a republic, in exchange for socialist participation in government.