Interregionalism without automatic integration: European Union influence and political mediation in Mercosur

This study empirically analyses the interregional influence of the European Union (EU) on Mercosur's economic integration between 1995 and 2024, explicitly incorporating the conditioning role of Mercosur's internal political context. Moving beyond normative assumptions of integration as an automatic institutional outcome, the study conceptualises integration as an observable variable through the construction of a Mercosur Economic Integration Index (MEI) based on a structural gravity framework. Methodologically, it adopts a mixed longitudinal design combining: (i) a geographical influence model capturing EU hard, soft, and independent power; (ii) a Bayesian causal impact model to assess political transitions; and (iii) a structural gravity econometric model to evaluate intraregional integration. Results indicate that EU influence does not produce homogeneous effects. On average, stronger European influence is associated with lower intraregional integration, suggesting external anchoring dynamics. However, this effect is significantly moderated by favourable internal political configurations, under which European influence may align with integration objectives. The findings highlight the politically contingent nature of interregional influence and underscore the importance of political economy perspectives in regional integration analysis.