'There is no union renewal without striking' has been the underlying logic driving collective bargaining and union renewal dynamics in the Basque Country. This article shows how the Basque sovereigntist unions ELA (Euskal Langileen Alkartasuna) and LAB (Langile Abertzaleen Batzordeak) have formed a 'counterpower' bloc, in opposition to CCOO (Comisiones Obreras) and UGT (Union General de Trabajadores) that are more prone to engage into social dialogue. The formers' renewal strategy based on organizing workers 'deeply' - especially with ELA's recurrent use of a strike-fund that fosters membership participation and affiliation through confederal solidarity - has altered union politics in the Basque Country. This has produced very high strike rates since the 2000s, perhaps the highest in Europe, and a 'spill over' effect that polarizes union alliances substantially. The article brings out the question of how unions could possibly locate industrial conflict within their renewal strategies and transform their organizations accordingly. Methodologically, the article contributes to the literature on strikes by underlining the importance of studying strikes critically, as a conscious collective process, in order to understand that their uneven development also derives from concrete unions' strategies.