The Loya Jirga, or Grand Assembly, will bring together 500 delegates from around the country to finalise a new constitution ahead of Afghanistan's first-ever presidential elections next year.
But two years after the Taliban's overthrow, the United Nations issued stark warnings this week that efforts to save Afghanistan could fail without more international commitment, and polls might have to be delayed because of rising violence.
Washington is trying to persuade its allies to follow its lead and step up aid in what analysts see as a attempt to present Afghanistan as success story in the coming election year to balance against the gloom of Iraq.
But no one seems ready to provide thousands more peacekeeping troops the country desperately needs.
Attacks stepped up
Since US Defence Secretary Donald Rumsfeld visited Kabul in May and declared major warfare over, Taliban and allied Islamist fighters have stepped up attacks around the country.
More than 400 people have died in attacks or clashes since then, the bloodiest period since the Taliban's overthrow.
Donald Rumsfeld inspects Afghan guard of honour
Rumsfeld's statement seemed even more premature this week when US military said it had launched its biggest ever operation to crush the Taliban and their allies.
It says the operation has helped prevent attacks to disrupt the Loya Jirga, but any positive impact has been diminished by the military's admission that 15 children died in two strikes last weekend against resistance leaders.
A statement from Taliban ally Qalb al-Din Hekmatyar carried
by Aljazeera overnight said Washington was demoralised in Afghanistan, just as it has been in Iraq.
"America has lost the war in Afghanistan and will leave this country soon," he said.
A resurgent Taliban has vowed to disrupt the Loya Jirga, which could last several weeks, calling it a US-staged charade and warning that anyone attending deserved to die.
Both President Hamid Karzai and US ambassador Zalmay Khalilzad have said the threat to the assembly is real, and last Saturday a bomb exploded in the city of Kandahar, wounding 18 people, in what Karzai said was part of the disruption campaign.
Even without the threat of attack, the Loya Jirga meeting will not be straightforward, as Karzai will be trying to persuade delegates to adopt a draft constitution that will give the president sweeping powers.
"(The Americans) can approve a constitution in whichever way they choose, either through pressure, cheating or distribution of money"
quoted by Reuters
He has vowed he will not stand in polls planned for next June if factional strongmen like Defence Minister Muhammad Qasim Fahim get their way and dilute the president's power by demanding a prime ministry.
Most delegates, be they democrats, Islamists or federalists or from any of Afghanistan's diverse ethnic groups, agree that Afghanistan, battered by 23 years of foreign invasion and civil war, needs a strong central government, but many fear that a strong presidency may open the door to a despot.
"We too want a presidential regime," said Qazi Abd al-Sattar, a delegate from the eastern province of Kunar, before heading over to Karzai's Kabul palace for lunch. "But we would like to have a parliament that can supervise the president.”
A simple majority is required to approve the constitution.
"Now the Americans want continuity," said a delegate who did not want to be identified. "They can approve a constitution in whichever way they choose, either through pressure, cheating or distribution of money.
"But if the document is not worked out on the basis of the majority's demands or plays down the role of Islam, then instability will gradually return to Afghanistan," the delegate added.
Foreign Ministry spokesman Umar Samad admits the government faces "a host of problems we can't ignore", but insists Afghanistan is making progress.
"We are moving along with political reforms and towards democratisation and that process is not going to stop," he said.
Four killed by US troops
Meanwhile, US special forces soldiers killed four "anti-coalition forces" who fired on troops after they had captured "a couple of people" in Jalalabad, 120km (75 miles) east of Kabul, a US military spokesman told reporters.
"The coalition troops returned fire killing four gunmen and wounding one," Lieutenant Colonel Bryan Hilferty said, adding that nearly a dozen men were arrested by Afghan police.
US soldiers have clashed with regional militias
Nangarhar provincial authorities said the people they caught included an Afghan militia commander and his men from neighbouring Laghman province. They were arrested during a regional military meeting in Jalalabad.
A Nangarhar security official said on Thursday that fighting erupted when US troops tried to arrest General Asmat Allah, Laghman brigade commander, during a regional military meeting near Jalalabad University.
Disarming militias is one of the priorities for Karzai as he attempts to extend the authority of his government.