The article examines the political relationship between Argentina and Brazil, which has been a central feature of the Southern Cone since the leadership of Raúl Alfonsín and José Sarney. This relationship transformed historic distrust into strategic cooperation, serving as an institutional design intended to stabilize the region, expand markets, and pursue a path of economic openness aligned with democratic practices. Despite occasional governmental differences, the article emphasizes the importance of maintaining the fundamental agreement of bilateral cooperation as a core of the Mercosur bloc.

As Mercosur evolved, it adopted aspirations that did not always align with South American realities, particularly through its efforts at customs union and a common external tariff, which were inspired by the European integration model. However, the experience in South America quickly revealed the limitations of such integration, as structurally protectionist economies faced pressures from sectors benefiting from trade barriers. This led to a proliferation of exceptions and adaptations that undermined the coherence of the Mercosur initiative.

The article concludes emphasizing that despite varying governmental landscapes and the push for further integration, the foundational cooperation between Argentina and Brazil remains crucial for Mercosur's future. It suggests that a realistic approach considering the unique economic and political contexts of member countries is essential for the sustainability of the bloc, advocating for cooperation that is adaptable and grounded in the realities of the region's diverse economies.