1 “Divide et impera”? Office accumulation in state-wide parties and the process of decentralization in Spain Javier Astudillo Universitat Pompeu Fabra Department of Political and Social Sciences Ramon Trias Fargas 25-27 08005 Barcelona, Spain javier.astudillo@upf.edu DRAFT VERSION: SEPTEMBER 2010 Abstract Most recent studies about internal power distribution within state-wide parties in previous unitary countries, like Spain, show that they have changed less than it was initially expected. But how national party leaders are able to counteract the decentralizing pressures that the first studies in this field underlined is still to be explained. In this article we reformulate a mechanism for national political leaders to have their parliamentary parties under control that Van Biezen has suggested for new European democracies. We argue that keeping party and public offices apart at the regional level is a vital part of a chain of command whereby national party leaders are able to control their party’s regional governments. Using for the first time a quantitative analysis of national and regional elites we show that office overlapping is thus substantially less intense at the regional level that at the national level in the two main Spanish state-wide parties, and that this feature is related to regional politicians’ degree of autonomy. Still, this ‘divide et impera’ strategy is less employed over time. I. Introduction In the last 30 years a large number of European and Latin American countries have experienced a transformation in their government structure (Rodden 2004). The creation of regional governments has developed a new arena of political competition and policy- making. This poses great challenges and strains on political parties. Initially, it was expected that the adoption of decentralizing institutional reforms triggers in turn the decentralization of state-wide parties (Maravall 1991, Hopkin 2003). More recently