Danish Prime Minister Mr Anders Fogh Rasmussen issued a final warning today that the bloc's historic enlargement could yet be derailed if no deal is reached at a landmark summit this week.
He also reiterated that the summit could be extended into the weekend if agreement is not reached by the scheduled end Friday.
"Enlargement can still go off track, it can be postponed for several years. Let's not gamble with this fantastic common prize, we'll all benefit from enlargement," said Mr Rasmussen, who will host the summit.
"Now at this summit we have a chance... to put behind us decades of division and bloody conflict. Thirteen years after the Berlin Wall was torn down, we have a chance to reunite Europe, this is an opportunity not to be missed."
In a letter to fellow heads of government preparing for the summit, which is expected to invite 10 mostly ex-communist states to join the EU, he said he hoped an accord could be reached by Friday. "However, the presidency is prepared to continue the meeting into the weekend if that should prove necessary in order to achieve the results aimed for," he added in the letter.
Most of the would-be EU countries have either struck deals with the EU or are near to agreement, but heavyweight candidate Poland, by far the biggest of the EU hopefuls, is taking talks down to the wire.
Mr Rasmussen has several times recently warned that enlargement could be delayed if candidate states demanded too much. He has also said that he has booked the summit conference centre through the weekend. Poland's chief negotiator Mr Jan Truszczynski said it was unimaginable that the EU would present candidates with a "take-it-or-leave-it" offer at the summit.
The presidency has repeatedly said it has offered candidates as much as it can in terms of farm aid and other benefits, and has already offered candidates an extra euro1.6 billion as a further carrot.
AFP