Delegates at talks to end Sudan's 21-year civil war are said to have resolved key remaining thorny issues holding up a final peace deal.
Both sides have already resolved some difficult issues
The government and southern rebels have agreed on the status of three disputed areas - including oil-rich Abyei - and on how to share power, officials say.
Three protocols are due to be signed on Wednesday in Kenya, paving the way for a permanent end to hostilities.
The talks do not cover the conflict in the western region of Darfur.
The two-decade old war pitting the Muslim-led government against Christian and animist rebels from the south has cost more than two million lives.
Until now the talks have stalled on how power would be shared in a transitional administration, on whether the capital, Khartoum, is governed under Islamic law and how Abyei, the Nuba Mountains and Southern Blue Nile regions will be administered.
"The protocols represent a major step towards the achievement of a final comprehensive settlement to the conflict," said a statement from Kenya's foreign ministry.
Power-sharing, Sharia in Khartoum
Status of Abyei
Status of Nuba Mountains, Southern Blue Nile
The two sides have already established that the south should be autonomous for six years, culminating in a referendum on the key issue of independence, with Sharia remaining in the north.
Protocols have also been signed on how to share out oil revenues, the establishment of separate monetary systems in the north and south and security arrangements involving the two armies.
It is hoped that a final peace treaty between the government and the southern rebels of the Sudan People's Liberation Movement (SPLM) could be signed as early as next month.
The United States has been pushing for both parties to finalise the deal after 22 months of negotiations.
From Ethiopia, Sudanese Foreign Minister Mustafa Osman Ismail told Reuters news agency he understood an agreement had been reached.
"Tomorrow will be the final day and they will sign the final agreement on the three outstanding issues... which opens the door for the preparation of the final text of the agreement," he said.