Army generals and protest leaders are on Wednesday expected to finalise the make-up of a new body to govern Sudan for three years, the thorniest issue in installing civilian rule.
The protest movement that brought down president Omar al-Bashir after 30 years of iron-fisted rule is demanding a civilian-led transition, which the generals have steadfastly resisted since bowing to their demands and toppling the autocrat.
The latest breakthrough came despite the overall talks being marred by violence that left six people dead late on Monday in and around a sit-in held by protesters outside the army headquarters in Khartoum.
Wednesday's crucial negotiations are due to start at 9:00 pm (1900 GMT), said Khalid Omar Yousef, a leader from the protest movement the Alliance for Freedom and Change.
"The announcement is expected after midnight," he told AFP.
The current talks began on Monday and the two sides have since agreed on an overall civilian structure, including a three-year transitional period for the full transfer of power to a civilian administration.
They have also agreed that parliament be composed of 300 members for the transition, with 67 percent from the Alliance for Freedom and Change and the rest drawn from other political groups.
The first six months of the transition would be devoted to reaching peace accords with rebels in war zones including Darfur, Blue Nile and South Kordofan.
But the composition of the new sovereign council has been the toughest part of the negotiations, with the two sides so far offering different make-ups of the body which is expected to take all key decisions concerning national issues.
The generals want it to be military-led, while the protesters insist on a majority civilian body.
"We vow to our people that the agreement will be completed fully within 24 hours in a way that it meets the people's aspirations," General Yasser al-Atta, one of the members of the current ruling military council, told reporters on Wednesday.
'All powers with cabinet'
The new council is expected to form a transitional civilian government, which in turn would prepare for the first post-Bashir election after the three-year changeover period ends.
The protest leader Yousef downplayed the role of the proposed ruling council, insisting the country would have a powerful cabinet.
"All powers will be in the cabinet's hand, which will be formed by the Alliance for Freedom and Change," he said.
"Only the ministers of defence and interior are going to be with the military."
He also reiterated the protesters' demand that the "majority of the (sovereign) council members must be civilians".
Tensions have soared this week as deadly violence erupted at the site of the long-running sit-in protest outside the army complex in Khartoum.
The shootings that killed five protesters and an army major on Monday came a day after protesters blocked Nile Street, a key avenue in the capital, which the generals said was "totally unacceptable".
The United States blamed the army for the deaths.
They "were clearly the result of the Transitional Military Council trying to impose its will on the protesters by attempting to remove roadblocks", the US embassy in Khartoum said in a statement on Facebook.
"The decision for security forces to escalate the use of force, including the unnecessary use of tear gas, led directly to the unacceptable violence later in the day that the TMC was unable to control," it added.
'We are optimistic'
The United States has consistently called on the military council to transfer power to civilians, while Sudan's Arab allies Saudi Arabia, the United Arab Emirates and Egypt have thrown their weight behind the generals.
The protest movement, after initially blaming the militias of the former regime for the bloodshed, later accused the military council.
"We put the whole responsibility on the military council for what happened yesterday because it's their direct responsibility to guard and protect the citizens," Mohamed Naji al-Assam, a prominent figure in the movement, told reporters on Tuesday.
Thousands of protesters meanwhile remain camped outside the military complex in central Khartoum awaiting the outcome of the ongoing talks.
The sit-in has become the focal point for the protest movement, overtaking the near daily protests that had been held across Sudan while Bashir remained in power.
One of the protesters, Mohamed Adam, said he was happy about the way the negotiations have turned out so far.
"We are optimistic about the agreement... because it represents victory for the Sudanese people over the remnants of the former regime," he told AFP.