Until very recently, officials in Brussels liked to describe enlargement as the EU's most effective foreign-policy tool.
The prospect of EU membership helped transform large parts of the ex-Soviet bloc, contributing eight new members to the bloc. The 2004 enlargement itself has been declared an economic success.
Yet something has gone wrong somewhere. Enlargement has become one of the most divisive issues in the EU, forcing its way to the top of the agenda of the current agenda.
"Enlargement cannot proceed bureaucratically, or not even diplomatically," European Commission President Jose Manuel Barroso said. "It has to be done democratically. And we have to win the confidence of the public opinion in Europe."
At its most elementary, the debate pits advocates of "deepening" against proponents of "widening." The former value deeper political integration, while the latter are mostly skeptical about integration and would prefer to extend the EU's benefits as far as possible.
In the middle of the debate stands the European Commission, the EU's executive. EU Enlargement Commissioner Olli Rehn argued today that the rift is dangerous and misconceived.
"In the current debate, we often talk past one another," Rehn said. "Some underline only the strategic significance of enlargement for peace and democracy. Others emphasize only internal problems which reduce our capacity to integrate new members. If these two discourses do not meet, we risk increasing confusion among our own citizens and an erosion of our credibility in the candidate countries."
Deep Or Wide Or Deep And Wide
Rehn's appeal for going ahead with "deepening" and "widening" simultaneously is likely to fall on deaf ears, however.
France, Germany, the Netherlands, and Austria are among the most skeptical member states. While they are likely not to veto the summit's expected confirmation of the EU's continued commitment to further enlargement, they will be looking to advance their cause in the finer print.
Thus, the summit will see the strengthening of the emphasis on the EU's need to be ready to accept new members -- its "absorption capacity." Before each new decision, impact assessments will be required, offering further means for the skeptics to put spanners in the works. France has already gone further and taken out the ultimate insurance policy of committing itself to hold referendums on each new entrant after Croatia.
The skeptics are now united less in their concern that the new member states owe too much allegiance to the United States, prevalent a few years ago, than by their domestic woes. All have large, mostly Muslim, and increasingly ill-adjusted immigrant communities, prompting introspection among their public opinion. Their publics seem to believe the EU is not delivering what it should and partly blame enlargement for what they perceive as the dilution of the bloc's original goals. Not coincidentally, France and the Netherlands were the two countries this year to reject the new EU constitution in referendums.
Integration At Home
Also not coincidentally, another key issue at the summit will be immigration -- how to roll back the waves of hundreds of thousands of desperate people every year risking their lives to reach Europe.
The notion that the EU should look inward at its own problems and goals before looking outward again to consider taking in new members is now becoming a commonplace in Brussels.
At the European Parliament in Strasbourg on December 13, European Commission President Jose Manuel Barroso made explicit the link between further enlargement and the consent of the European publics.
"Enlargement cannot proceed bureaucratically, or not even diplomatically," Barroso said. "It has to be done democratically. And we have to win the confidence of the public opinion in Europe."
Among the casualties of the bloc's malaise over enlargement are the would-be candidate states for membership that have never managed to win official EU acknowledgement of their aspirations.
There will be no meaningful debate at the summit of where Europe's borders might lie. Rehn has argued against such a debate, saying the current generation cannot fix the borders of the EU any more than the last one could.
Put another way, this means, however, that in the foreseeable future, the EU will only have time for its candidate countries. Finland's deputy foreign minister, Paula Lehtomaeki, made this very clear in her expose to the European Parliament of the summit's agenda as compiled by the EU's outgoing Finnish presidency.
"The enlargement debate [at the summit] aims to consolidate the commitments that we have made to Croatia and Turkey, both now engaged in membership negotiations, and also to the western Balkan countries," she said. "As far as the outcome of the European Council's enlargement debate is concerned, our aim is to agree on a renewed consensus on enlargement."
And even within the candidate-member category there are no foregone conclusion, as Turkey's experience earlier this week shows.
The EU put on hold eight of the 35 negotiating chapters, ostensibly to penalize Ankara for not accommodating the Greek-community government of EU member state Cyprus, but equally at the behest of France, Austria, and the Netherlands, who all stood behind Nicosia.
To view RFE/RL's archive of coverage related to EU expansion, click here .