EU enlargement policy is shaped not only by the member states, the Council of the EU or the European Council but also by the Union supranational institutions. The aim of this article, which makes use of the decision method, is to show that mechanisms of the multi-level governance (MLG) are also present in this policy. This enables a researcher to verify, with the use of MLG as the theoretical model, the hypothesis that the continuation of the enlargement process depends on the capacity of the supranational institutions influencing the decisions made by the member states whose approach to admitting new countries to the EU is increasingly reserved.