The largest of the rebel factions in Sudan's Darfur region has agreed to sign a peace plan with Khartoum.
A leader of one faction of the Sudan Liberation Army (S.L.A.), Minni Minnawi, says he has accepted an amended peace agreement, although reports say he has expressed reservations.
Two other rebel groups -- the Justice and Equality Movement and an S.L.A. faction led by Waheed Al-Nur -- have rejected the proposal outright.
The international community has been applying heavy pressure on negotiators in Abuja, Nigeria, to reach a peace deal to end three years of violent conflict.
Negotiators from the United States have taken a prominent role since Sunday, when rebel leaders rejected a Sudan-approved draft agreement.
Mediators had been trying to negotiate new terms that give the rebels more political power and integrate them into Sudan's military, while disarming Arab militias in Darfur.
President Bush said Thursday the rape, murder and suffering in Darfur must stop, and that genocide will not be tolerated.
The deadline for reaching a peace deal has already been extended twice. Conflict about land and water resources in Darfur erupted into fighting in 2003 when non-Arab rebels accused the Arab-dominated government of neglect.
Fighting among the rebels, government forces and Khartoum-backed Janjaweed militias has killed at least 180,000 people and displaced more than two million others.