EU foreign ministers met again on Monday, hours after the end of tense late-night meetings between the British EU presidency and Austria that did little to allay fears Turkey's long-awaited rendezvous could be pushed back.
The Austria-Britain talks were held after EU foreign ministers failed, in a meeting late on Sunday, to resolve the standoff.
"It's a frustrating situation, but I hope and pray that we may be able to reach an agreement," said British Foreign Secretary Jack Straw, as the calendar ticked over to 3 October, the date set for talks with Turkey to begin.
And the likelihood that talks would not start by 5pm became all the more likely after a Turkish official said Ankara rejected any proposed changes to its framework agreement to opening the accession talks.
Foreign Ministry spokesman Namik Tan said that "the EU has proposed some changes to the framework document. Our minister has rejected them all".
Visibly tired at a late-night news conference, Straw said that in theory the deadline for an agreement was 1500 GMT. "That's still not impossible, but it could slip. Nothing is certain," he said.
Austrian Foreign Minister Ursula Plassnik refused to bow to the pressure of being confronted by all her fellow European Union members.
"We are not afraid of difficult situations," she told reporters after another round of talks with Straw. "There are limits, and we are about to explore them now."
British Foreign Secretary Jack
Straw has tried to end the delay
In Ankara, Turkish Foreign Minister Abdullah Gul huddled with his advisers awaiting news that never came that Austria had ceded ground. Despite its EU ambitions, Turkey has threatened to turn its back if Vienna gets its way.
After four decades of knocking at Europe's door, the predominantly Muslim country was given a date of 3 October to start talks by EU leaders in December.
But Ankara's recent insistence that it would still not recognise EU member state Cyprus, in a declaration attached to a customs agreement in July, created strains weeks before its long-awaited date.
The present dispute focuses on the wording of the "negotiating framework" for the accession talks - essentially their guiding procedures and principles - which Austria wants to refer to something other than full membership.
Plassnik insists that Vienna is not against starting the EU talks with Turkey but just wants them conducted on the right terms.
"There is no question that we are for the start of negotiations," she said. "But in order to agree to that we need a text which is a little bit better. We are working on that. It is not particularly easy."
"Either the EU will decide to become a world force and a world player ... or it will limit itself to a Christian club"
Recep Tayyip Erdogan,
Turkish prime minister
But it is difficult to see exactly what change of wording is needed.
The current draft - accepted by all 24 other EU states - says that EU entry is the main aim of the talks. Vienna would like that tempered with another formula, if not replaced altogether.
Nevertheless, European enlargement commissioner Ollie Rehn remained optimistic. "I am confident that we shall have a positive outcome and start negotiations tomorrow (Monday)," he said.
The new delay has angered the Turkish public and politicians.
Prime Minister Recep Tayyip Erdogan, whose country has undergone tough political, economic and social reform to join the union, warned the EU against refusing to start the talks.
"Either the EU will decide to become a world force and a world player ... or it will limit itself to a Christian club," he said.
One unknown factor is how much stock Austria puts in neighbouring Croatia being given the green light on Monday to start its own delayed talks.
Croatia was to have started EU entry talks in March, but its case has been held up by its lack of cooperation with the UN war crimes tribunal, notably over a key war crimes suspect, fugitive general Ante Gotovina.
The dispute over Turkey has also delayed a meeting of a special EU task force that was set to discuss the progress it had made at 9.30am.
It was unclear overnight when that meeting would take place.