The electoral success of the populist radical right has posed a significant challenge to the mainstream left over the past few decades. While academic literature has yet to reach a consensus on voters’ shift from the left to the radical right, some studies have nonetheless assessed the strategies that Western European Socialist parties have adopted to counter the new threat. Among these, particular attention was given to cases in which the radicalism of the competitor was co-opted into the mainstream left-wing agenda, with the most notable example being the Danish Socialist Party. This paper draws attention to the Central and Eastern European context, where the nexus between the crisis of the left and the success of right-wing populism is instead widely demonstrated. The paper relies on qualitative case studies and semi-structured interviews to party elites and experts; it primarily focuses on the Bulgarian Socialist Party and Romania's Social Democratic Party, which have adopted, respectively, a positive and negative strategy of engagement vis-à-vis the populist radical right. Such divergence is determined by the socialists’ organizational and programmatic evolution, their international positioning and the willingness of other parties to isolate the populist radical right. The position of the two actors on the Russian invasion of Ukraine emerges as the stronger explanatory variable in determining socialists’ stance towards the far-right. The results are tested on two control cases, Czechia’s Communist Party of Bohemia and Moravia and Slovakia’s Smer-SD.
