Coalition formation in European Parliament

This bachelor’s thesis applies methods from cooperative game theory to analyze coalition formation and voting power in the European Parliament. The central objective is to quantify the influence of political actors, particularly Czech political parties, using the Shapley-Shubik power index. A two-dimensional analytical framework is employed, incorporating both ideological coordination (at the level of European political groups) and national coordination (within member state delegations). The thesis introduces a weighted model that reflects empirical findings suggesting ideological alignment dominates most voting behavior in the Parliament. Through mathematical modeling and empirical simulation based on the 2024 European Parliament election results, the study estimates the probability of each party being pivotal in coalition-building. The results reveal that a party’s power is not determined only by the number of seats it holds, but also by its structural role in the broader institutional setting. This approach offers a nuanced understanding of strategic influence and contributes to the study of institutional decision-making in supranational legislatures.