Decentralization and the Regionalization of Party Systems

Does decentralization reverse the party system nationalization process? We argue, decentralization is not a precise mirror image of centralization. The fundamental difference between centralization and decentralization for party system dynamics lies in the different adaption strategies for parties and voters that both processes unfold. We argue that decentralization is likely to reinforce fragmentation on the regional level despite the consolidation incentives proposed by the party system nationalization literature. In order to test our theoretical argument we use a novel dataset with information about regional elections and 16.800 partisan electoral records in 13 countries and 217 regions from 1945 to 2017. We apply entropy balanced regressions in order to put our argument under scrutiny on the party as well as on the regional party system level until six elections after decentralization reform. The results indicate that fragmentation rises in Rokkan as well as non-Rokkan regions in the long-run. The effect of decentralization on fragmentation is sizeable and outweighs, for example, the change of an electoral system or the general fragmentation trend in democracies. Thus, the decentralization trend will most likely not lead to return of provincial politics but to the simultaneous importance of several territorial levels which will predominantly challenge state-wide parties’ abilities to maintain adequate degrees of internal cohesion.