EU foreign ministers are to hold emergency talks in Luxembourg on Sunday in a last-ditch effort to break the deadlock over Turkey's membership bid.
Turkey's EU ambitions have ignited a heated debate
The UK called for the meeting after EU ambassadors failed to agree on a joint negotiating framework on Thursday.
Austria has demanded there should be an alternative to full Turkish membership - an option rejected by Ankara.
Accession talks with Turkey are due to open in Luxembourg on Monday - provided Turkey accepts the framework for talks.
"No one expects us to go to Luxembourg before seeing the negotiation framework document," said Turkish Foreign Minister Abdullah Gul, adding there was a possibility that negotiations would not start.
He then underlined that everybody was working hard to overcome the hurdles, and that there was still time to solve the problems.
Speaking on television later on Thursday, Prime Minister Recep Tayyip Erdogan said he was confident an agreement would be reached.
He said the document could still be presented until right before the talks start early on 3 October.
Diplomats say Austria is insisting that Turkey be offered a partnership with the EU as an explicit alternative to full membership.
Turkey has made it clear that it will walk away rather than negotiate for anything less than full membership.
The BBC's Sarah Rainsford says many in Turkey feel tricked by Europe, which they see as constantly moving the goalposts for accession.
The negotiations, once started, are expected to take about 10 years.
Italy backs Turkey
Turkey needs to make huge efforts to meet the stringent requirements for EU membership, including absorbing the 80,000-page EU rule book into its domestic law.
The European Commission has promised to monitor closely how Turkey proceeds. If it is deemed to be slipping backwards in theory or practice, then the commission will not hesitate to make its misgivings public.
In an open letter published on Thursday Italy's Foreign Minister Gianfranco Fini said Turkey had "fully satisfied the conditions" laid down for opening membership talks on 3 October.
Turkey's bid represented "an opportunity for a major relaunch of the entire European project," he said, calling for an end to "our selfishness and uncertainties". His letter was published in the Italian daily Corriere della Sera.