Although the European Commission recommended in September that Turkey fulfill the political criteria to start membership talks, EU member states with a final say are having second thoughts.
The biggest skeptics include France, Austria, and Cyprus -- a new EU member that is still not recognized by Ankara.
Earlier this week, a leaked draft statement being prepared by the EU's Dutch presidency for the 16-17 December summit emphasizes tough conditions for starting entry talks.
Today, European Commission officials appeared to acknowledge that views are hardening. Francoise Le Bail, a commission spokeswoman, called the draft a "work in progress" but suggested that new, possibly favorable elements could find their way into the summit statement.
"The commission believes that the proposal it has made in September, it's a balanced one. It is quite natural now that there is a debate in the council and we are confident that we will find a balanced solution, a solution that will take into a great part of what the commission has proposed in September," Le Bail said.
Crucially, the summit draft does not contain what has been Turkey's key demand: a start date for entry talks.
EU officials say a debate is raging within the union. A number of influential countries, led by France, do not want Turkey to be an issue during preparations for the ratification of the new EU constitution next year.
One official told RFE/RL that the December summit could put off naming a date for accession negotiations, announcing instead the immediate start of pre-talks aimed at "screening" Turkey's positions. This would fall well short of Turkey's expectations. Ankara is said to prefer even a late date to no date at all.
One of the biggest hurdles for Turkey's entry is the Cyprus problem.
The draft summit statement said Turkey would have to recognize the Greek Cypriot government as rulers of the whole island, just like the rest of the EU. Cyprus joined the EU with nine other new members in May, but Turkey continues to back a breakaway Turkish Cypriot state in north Cyprus.
The draft also appears to toughen measures to enable members to keep Turkish workers out after EU entry. And it specifies that EU members may request breaking off entry talks at any point if they see Turkey as not living up to EU standards.
The draft also confirms an earlier European Commission view that no financial provisions for a Turkish accession can be made before the budget cycle starting from 2014.
A report adopted by the foreign affairs committee of the European Parliament today says EU membership is not the "automatic consequence" of entry talks. Although a reference to a "privileged partnership," falling short of actual membership, was voted out of the report, this option is gaining credence in some EU states.
Austria's center-right government, France's ruling conservatives, and the conservative opposition in Germany are all campaigning for a limited "special partnership" for Turkey.