It is of course, for the politicians to decide on this. In my view, the countries of Central and Eastern Europe should be given enough time to prepare themselves properly for becoming part of the Single Market. Moreover, given the substantial differences among them, the candidate member states should be looked at on a case-by-case basis.
Some transitional provisions are likely to be necessary for new member states after joining the European Union. Without such provisions the expansion of the European Union may need to be postponed for many years, which is clearly undesirable. Moreover, in the past such provisions have also been applied to new entrants, including Spain, Portugal and Greece. It is essential to strike a proper balance.