Ideological cleavages beyond the nation-state: The emergence of transnational political groups in international parliaments

Territorial divisions are commonly believed to dominate the international realm, supposedly leaving no room for ideological distinctions to take shape. However, the formation of over fifty transnational political groups (TPGs) across thirteen international parliaments challenges this assumption, calling into question the previously accepted insignificance of ideology beyond the boundaries of the nation-state. Previously unexplored in comparative perspective, this paper investigates TPGs’ puzzling existence and delineates the conditions for their emergence within international parliaments. The theoretical argument is that homogeneity across the member states of the international parliament along three dimensions – political systems, economic development levels and geographical proximity – fosters the creation of transnational political groups. Results from regression analysis on time series cross-sectional data lend support to the theory. With the rise of international parliamentary institutions and their increased involvement in supranational decision-making over time, it becomes highly important to understand how they organize as well as the implications of their institutional designs.