The Sudanese government on Sunday accepted a peace plan for the Darfur region that requires it to disarm Janjaweed militias before rebels lay down their weapons in what diplomats said was a major breakthrough.
But the rebels, under intense international pressure to also accept the 85-page settlement drafted by African Union (AU) mediators, struggled to extract last-minute concessions and had yet to give a clear signal on whether they would sign.
The AU had set Sunday as a deadline for the government and two Darfur rebel groups to wrap up negotiations that have dragged on for two years while the conflict in the vast western region of Sudan has escalated.
"The government ... wishes to confirm its decision to formally accept this document and its readiness to sign it," said a statement from Majzoub al-Khalifa, head of the government's negotiating team at peace talks in Abuja, Nigeria.
The government said it had decided to sign despite "reservations", and diplomats said the biggest of those centred on disarmament arrangements.
"What this (agreement) means, in effect, is that the government has to disarm the Janjaweed at a time when the rebels will still have their forces fully deployed, albeit in defensive positions," said a diplomat closely involved in the talks.
Rebels took up arms in early 2003 in ethnically mixed Darfur, an arid region the size of France, over what they saw as neglect by the Arab-dominated central government.
Khartoum used militias, known locally as Janjaweed and drawn from Arab tribes, to crush the rebellion. The fighting has killed tens of thousands of people while a campaign of arson, looting and rape has driven more than 2 million from their homes into refugee camps in Darfur and neighbouring Chad.
All sides have continued fighting despite a 2004 cease-fire, according to the AU, which has 7,000 peacekeepers in Darfur.
"SAVE DARFUR" RALLIES: In the United States, President George W. Bush has called the violence "genocide" and endorsed a series of "Save Darfur" rallies planned for later on Sunday to put pressure on Khartoum to stop the violence.
Diplomats said the AU was making preparations for AU Chairman Denis Sassou Nguesso and AU Commission Chairman
Alpha Oumar Konare to come to Abuja in anticipation of a possible signing ceremony on Tuesday.
At the venue of the peace talks, a no-frills hotel on the dusty outskirts of Abuja, diplomats and Sudanese delegates bustled from one meeting to the other in the race to hammer out an agreement by the end of the day.
Diplomats said a trade-off was still possible whereby the government would grant the rebels a few concessions in exchange for a watering down of the Janjaweed disarmament provision.
The rebels were still talking amongst themselves to seek a consensus on whether to sign. Decision-making is an arduous process for them as they are split into two movements and three factions with a history of infighting.
The rebels complain that the agreement does not meet many of their key demands in the three main areas of security, power-sharing and wealth-sharing. But observers say they would have little to gain by rejecting the AU's plan.
One faction of the Sudan Liberation Army (SLA), led by Abdel Wahed Mohammed al-Nur, gave an official response to the draft that was not clear-cut. They listed their objections and the AU told them to take their concerns directly to the government.
The other SLA faction, led by Minni Arcua Minnawi, together with the smaller Justice and Equality Movement (JEM), were due to meet the mediators at 1500 GMT to present their position.
The government's statement suggested any outstanding issues could still be solved after a signature.
"The delegation is also fully convinced that any difficulties that might come up in the implementation stages can be resolved by consensus between all the parties," it said.
But some rebels said they were sceptical of this assurance.
Several previous deadlines have passed without any apparent impact on the discussions. But this time AU mediators say they mean business and if the sides reject the draft, the AU Peace and Security Council will decide on a new strategy.
Aid groups say increased fighting in Darfur has made it impossible to deliver food and medicine to tens of thousands of refugees in Darfur and in camps across the border in Chad.
UN Commissioner for Human Rights Louise Arbour, now in Khartoum, will visit the South Darfur capital Nyala on Monday and the West Darfur capital El Geneina on Tuesday.