They dont get the full rights of states of the union with EC votes and all that until they have proven themselves free of all vestiges of communism. Otherwise its like trying to graft a gigantic cancer tumor onto a body.

Just like how Rome had adjacent provinces taken by treaty or military that had high unrest and centrally appointed consuls and praetors, and supervisory military footprint to keep order. And had to progress and upgrade their way to being a fully autonomous and viable state with the rights of citizenship over a period of time.