International Treaty Ratification and Party Competition: Theory and Evidence from the EU's Constitutional Treaty

What explains a party’s dual decision to endorse or not endorse a referendum on an international treaty and to support or oppose that treaty in a referendum campaign? Treating referendums as second-order elections with an uncertain outcome we propose a probabilistic game of electoral competition between government and opposition, wherefrom we derive a number of hypotheses regarding the impact of timing, public opinion and political capital. Data on the position of 175 parties in 24 member states of the European Union (EU) on the appropriate ratification instrument for the EU’s Constitutional Treaty and their substantive position with respect to the Treaty itself allow us to test these expectations against empirical evidence. The results of a multinomial logistic regression model provide solid support for our theoretical reasoning. The last two decades have seen a substantial number of facultative referendums for the ratification of international treaties. The most prominent examples are the referendums for the ratification of institutional reforms in the European Union (EU). In 2005 and 2006, for example, France, Poland, the United Kingdom, and several other countries either held or planned to hold referendums on the EU’s Constitutional Treaty (also known as the Treaty Establishing a Constitution for Europe [TECE]). Interestingly, other EU member countries, among them Austria, Belgium, and Sweden, decided not to submit the treaty to a popular vote. Even more variation exists when looking at party positions: in Spain all political parties represented in the national parliament called for