Party mergers in Italy and the UK : an Empirical Analysis

The aim of this work is to investigate those conditions that influence party mergers in Italy and the UK. The starting point are the theories of legislative organization, that focus on parties as the main organizational element of legislatures. The common point of these contributions is that parties are similar to firms. The extension of this framework is to think party mergers as firm mergers. Starting from the industrial organization literature it is possible to identify those incentives that should push two parties to merge together. A first motivation that we can stress is the “synergy” benefits. This means that the total value from the combination of the parties is greater than the sum of the value of the component parties operating independently. A second incentive is linked to the possibility to reduce the effect of a “war of attrition”. It is possible to consider that two political parties that have the same constituency could incur in repeated loss of votes over time because the supporters split the vote between them. Shifting from rational incentives to the institutional framework the literature on coalition formation underlines that disproportional electoral systems tend to force parties to coalescence before elections in order to exploit electoral economies of scale. To investigate those hypotheses, I will start performing a quantitative analysis. Data will be organized in dyadic form. This means that all the possible couples of parties for every election from 1948 to 1997 will be considered. The dependent variable will be built as a binary indicator: 1 if in the election taken into consideration two parties merge together; 0 otherwise. Among the independent variables I will consider seats received by the potential merger, number of parties, disproportionality of the electoral system, and left-right party policy positions. The results are quite encouraging, although they are very similar to the ones already noticed in the works on pre-electoral coalitions and coalitions.