In a number of cases, integration of a large international region or an interstate union can only be promoted by political means. The policy of regional economic convergence prevails in many sectors. The single economic market and membership in economic and monetary unions give a new impetus to consolidation. The study aims to identify and explore the problems of political governance, which the Union State of Russia-Belarus faces due to their asymmetric and not completely compatible economies. The author analyzes the process of interstate convergence, considering it as an essential part of integration and explores a number of specific characteristics underlying the Russian-Belarusian economic integration. The author offers a set of criteria of convergence/not convergence of the states, describes the principles of their economic and political rapprochement and offers models of convergence as well as prerequisites for them. The article examines the principles that determine the participation of a country in international integration as well as prospects for the further development of the regional economic and political mechanisms, which are being formed