The current study assumes that the notion of sustainable development, typical for the discourse on environmental protection, can be also applied to political research and indicates that institutions play a very important role in the process of creating and maintaining the balance of the political system, the aim of which is to build sustainable relations between different participants in its space. The European Union, which seems to feature characteristics of a hybrid organization and displays strong tendency to increase complexity, is examined. The EU institutions have a very important and often difficult role to play in sustaining intergovernmental and supranational influence and therefore often find themselves in contradictory situations. The intersecting efforts to deepen integration and at the same time the need to protect sovereignty do not allow for straightforward achievement of sustainable development of the integration system. Therefore, a distinctive feature of this system is the maintaining of sustainability rather than the actual achievement of sustainable development.