Afghan leaders met US and UN officials behind closed doors on Friday to try to end an impasse over a new constitution that has exposed ethnic fault lines and undermined Washington's vision of a strong presidential system.
The Loya Jirga, or Grand Assembly, descended into chaos on Thursday after about 200 of the 502 delegates refused to vote on amendments to the draft charter, and counting of the assembly's first ballot was suspended.
The assembly will resume on Saturday, by which time interim leader Hamid Karzai and his supporters hope to have won over opponents seeking to dilute his powers ahead of presidential elections in June.
The Western-leaning Pashtun, the country's largest ethnic group, has refused to water down demands for a strong presidency he feels is necessary to keep the war-shattered country together.
But compromises may have to be made to break the deadlock on issues such as the powers of parliament and the provinces, the rights ethnic minorities as well as the role of Islam in society.
"Behind the scenes, I think there are negotiations between the leadership of the Loya Jirga and leaders of the opposition," said a member of the Constitutional Commission.
"They want to agree terms on certain articles."
Leading the push for a stronger parliament are members of the Northern Alliance of mainly minority Tajiks who helped the United States topple the Taleban more than two years ago. Despite that, US allegiance is now firmly with Karzai.
The centralised presidential system outlined in the draft is being challenged by ethnic groups including Tajiks, Uzbeks and Hazaras, who are also calling for official recognition of their languages and more power for provinces where they live.
UN special envoy to Afghanistan Lakhdar Brahimi and US ambassador Zalmay Khalilzad were both involved in talks with delegates on Friday.
Saturday's session, if it takes place, will complete the third week of work at the giant white tent on a Kabul college campus - more than twice the 10 days set aside for the debate.
Karzai needs a simple majority to pass a version of the constitution suitable to him, but more walkouts by the Northern Alliance would badly damage the legitimacy of the process.
The fact that the stand-off is broadly between Pashtuns, seeking a return to their traditional role at the centre of Afghan power, and smaller ethnic groups mostly living in the north, has increased the stakes.
"I am...concerned that there is an ethnic polarisation that was unnecessary that could be, if allowed to continue, very damaging," the EU's envoy to Afghanistan Francesc Vendrell said on Thursday, adding that he hoped it was a "temporary explosion".
An Afghan official involved in the assembly said 280 to 300 delegates voted in Thursday's ballot. Their ballots would be kept locked up until the protesters could be persuaded to vote.
He told Reuters that some of those who did not vote were in fact Pashtun supporters of Karzai too afraid to take part because they came from areas of Afghanistan dominated by Uzbeks.
The draft constitution's 160 articles outline a presidential system of government with no prime minister, an Islamic republic without mention of the strict sharia laws enforced by the Taleban and respect for the rights of women and minorities.