--- - |2 Abstract With the 2011 ceasefire declaration the Basque patriotic left (IA) has committed itself more firmly to constitutional politics. Concurrently, Spain has experienced an upsurge in the popularity of new political parties in the historically two party dominant general elections. The emergence of a political challenger on the left of the political spectrum (Podemos) may pose an opportunity or a threat to the IA's unilateral strategy, as the parties have numerous points of ideological concurrence. This paper analyses how the IA seeks to translate its strategies into mainstream constitutional politics, by exploring how it responds to the question posed by Podemos – ally, competitor, or both? Using an historical institutionalist approach, the conditions at two critical junctures – those surrounding the formation of new political parties during the democratic transition period and the more recent change in the electoral landscape – are compared to assess the initial impact of Podemos on IA cohesion. - 'Nations and Nationalism, EarlyView. '