Divided parties, divided government

The U.S. phenomenon of divided government has its counterpart in a parliamentary system as a result of the politics of coalition. One legislative coalition may put the executive in place, a different legislative coalition may sustain it in a vote of confidence, while yet another legislative coalition enacts measures that thwart its day-to-day business. I explain such division between executive and legislature by relaxing the party-as-unitary-actor assumption and recognise that executive and legislative elements of the same party may pursue different strategies. Party leaders may enter into commitments to coalition partners that involve implicit or explicit obligations to impose intraparty discipline. Leaders may do this with greater or lesser enthusiasm, and the required discipline may or may not be forthcoming. Thus, governments may be defeated in legislative votes because the legislature fails to honour obligations entered into by the executive. This paper sets out a simple model of this process, begins to analyse it, and elaborates a recent real-world example of the phenomenon.