This paper explores the impact of decentralization upon the internal organization and electoral competition strategies of state wide parties by analysing variation of national and regional MP’s preferences over devolution in the two most important Spanish state-wide parties: the Socialist Party (PSOE) and Partido Popular (PP). We espouse the argument that decentralization spurs centrifugation dynamics within the internal organization of state-wide parties that results in (and is reinforced by) increasing variation between national and regional copartisans’ preferences over devolution. The hypothesis is tested using survey data gathered from more than 800 closed interviews to Spanish representatives in the national parliament and regional assemblies.
