It creates a Union Parliament for the Union's new citizens:-

The Lisbon Treaty/EU Constitution makes Members of the European Parliament, who at present are "representatives of the peoples of the Member States", into "representatives of the Union's citizens" (Art.9a, amended TEU).

This illustrates the constitutional shift the Treaty makes from the present European Union of national States and peoples to the new Federal Union of European citizens and their national states - the latter henceforth reduced constitutionally and politically to provincial or regional status.