The US Secretary of State, Ms Madeleine Albright, pulled out all the stops yesterday to convince ethnic Albanians to accept a Kosovo peace deal but failed to achieve a breakthrough.
Ms Albright spent hours trying to reassure the ethnic Albanian delegates, calling in NATO's supreme commander in Europe to France to brief them.
But State Department spokesman James Rubin told reporters: "We do not know what the outcome of their caucus will be."
US and European officials said privately there appeared little chance the talks would conclude for today's new deadline with a clear-cut acceptance from either Serbs or the ethnic Albanians.
That would dash prospects of NATO military action against Serbia or of a NATO-led peacekeeping force moving into Kosovo to guarantee an interim autonomy agreement.
In the most spectacular gambit, Albright had US Gen Wesley Clark, the supreme allied commander in Europe, fly into Villacoublay air base near Rambouillet, to brief ethnic Albanian leaders for an hour about just how quickly NATO could move troops in to protect them.
But the Albanians, who appeared to be constrained by Kosovo Liberation Army separatist guerrilla commanders in the field, stuck to their demand for a referendum on independence after three years and raised new concerns about the military arrangements, Western officials said.
The Serbian President, Mr Milan Milutinovic, appeared yesterday to soften slightly Belgrade's rejection of a NATO-led implementation force, saying an international military presence could be discussed once both sides signed a political accord.
In a move that might make it easier for Yugoslavia to accept an international military presence, Russia offered yesterday to contribute troops to an implementation force if it had a UN mandate and was invited by Belgrade.
The extended deadline for the talks expires at 2 p.m. today, and intense efforts to reach a resolution are expected this morning, with foreign ministers from Britain, Italy and Germany returning to Rambouillet.