New municipalism in Spain arose from a major political wave, now in a period of crisis and electoral retreat. This paper applies a regime-theoretic framework to analyse new municipalist governance in two smaller city cases: A Coruña and Santiago de Compostela. It argues that whilst new municipalist electoral victories inaugurated a crisis for established regimes, the crucial weakness was that they did not consolidate new urban regimes. Municipalists faced severe governability challenges linked to the enduring power of older urban regimes. The paper suggests that this is explained by problems in establishing regime incumbency, the consolidation of the necessary governing capacity by a resource coalition to deliver its agenda and succeed politically. Although established regimes were weakened enough to lose elections, they maintained considerable capacity to constrain the municipalist project and shape urban governance, a significant degree of incumbency. This ultimately enabled them to recover office in 2019. We argue that a critical regime-theoretical perspective assists in understanding the wider crisis of Spanish municipalism and the multi-scalar struggle for hegemony as it plays out in the local state arena.