Luxembourg's Jean-Claude Juncker, who will chair a crunch meeting of euro zone finance ministers on Monday, said efforts to slash Greece's debt from 160 percent of output to a target of 120 percent by 2020 were still "far away" from fruition.
"All the discussions I will have ... until Sunday night will try to move the figure nearer to the target," the head of the Eurogroup told reporters in his home capital.
Earlier, Greek caretaker Prime Minister Lucas Papademos talked to fellow euro zone leaders to persuade Berlin and others to back bailout measures needed to stave off bankruptcy.
German Chancellor Angela Merkel, Italy's Mario Monti and Papademos all voiced optimism about an accord during a three-way conference call, Monti's office said in a statement.
The Greek premier also spoke to Dutch Prime Minister Mark Rutte and state television said he would pursue talks with euro zone partners "to create a positive mood in view of Monday's meeting and to dispel doubts that could thwart this agreement."
A brief message by Rutte on his Twitter account noted simply of the call with Papademos: "I have pointed out to him that the Greek people should comply with all demands to get a new program."