The Afghan government will convene more than 2,000 Afghans from across the country this week to debate the country’s future relationship with the United States, a gathering that has drawn criticism from a skeptical political opposition that describes the process as antiquated and illegitimate.

The traditional Afghan meeting, known as a loya jirga, will begin Wednesday under a tent in Kabul, with the intention of soliciting Afghan input on President Hamid Karzai’s efforts to strike a strategic partnership agreement with the United States. U.S. and Afghan officials have been negotiating that document for months, but have yet to come to an agreement on the nature of American involvement in Afghanistan in the decade after 2014, when Afghan authorities are expected to be in charge of their own security.

“We’re going to listen to the people’s advice. This is a consultative jirga, where people will guide us,” said Shaida Mohammad Abdali, Afghanistan’s deputy national security adviser. “And their advice will be reflected in our ongoing negotiations with our U.S. colleagues.”

The Taliban have warned Afghans against participating in the gathering and vowed to disrupt it. The Taliban Web site published a document Sunday they claimed was part of the government’s security plan for the event, and said such intelligence would make their attacks “more lethal and precise.” Afghan authorities dismissed the document as a fake. A rocket attack at a peace conference in Kabul last summer marred the event and prompted the firing of two Afghan cabinet ministers.

The United States and Afghanistan have yet to agree on certain key issues about their proposed arrangement. Afghan officials have sought concrete commitments on how much the United States will fund Afghan soldiers and police — they are now almost completely reliant on American donations — as well as timelines on when they’ll be in charge of detentions and night raids. American officials have argued that they can’t promise funding from future U.S. administrations and that changes in American military posture should be flexible enough to take into account how the war with the Taliban is progressing.

For their part, American officials want to have access to long-term bases for their troops to pursue counterterrorism operations or address other regional issues that arise.

“The strategic partnership negotiations are ongoing, and there is no fixed timetable for the negotiations,” said one U.S. official in Kabul who requested anonymity to discuss the confidential negotiations. “Our concern is to get it right, not to get it completed by a certain date.”

Karzai’s opponents see the three-day jirga as a way for his administration to acquire a veneer of popular support for its agenda with Washington — or for more nefarious means. Several people said the reliance on such an ancient custom undermines the modern democratic institutions — such as parliament — that they’re struggling to empower. The effect of such a meeting, said Abdullah Abdullah, a former presidential candidate and opposition leader, is that “people will not trust their government.”

Many Afghan parliament members are skeptical about Karzai’s motives for convening the gathering, and some complained that the government had not shared with parliament a draft of the meeting’s agenda. Dozens of lawmakers planned to boycott.

Many have lingering suspicions that Karzai intends to use the meeting to garner support for some type of extension after his term, which expires in 2014, although Karzai has said he does not plan to change the constitution to pursue a third term.

“I would say Karzai plans to either change the constitution to prolong the duration of his government, or announce a state of emergency that will allow him to stay on in power,” said Shekiba Hashimi, a parliament member from Kandahar. “I will not take part.”

The gathering, which will be at least three days, will include some 2,000 Afghans from across the country, including lawmakers, provincial and district council members, representatives of refugees living in Pakistan and Iran, war wounded and women’s groups. Unlike a “constitutional” loya jirga, where the decisions reached are binding, the meeting this week will be a “consultative” jirga, whose main benefit for the palace is that the recommendations could bolster Karzai’s positions.

A massive tent donated by Germany has been erected at Kabul’s Polytechnical University for the jirga, the same venue that has housed similar meetings in the past decade since the Taliban government fell. Security is expected to be tight across the city.

Karzai called for the large meeting after the assassination in September of former president Burhanuddin Rabbani, who was serving as a peace envoy to negotiate with the Taliban. His killing threw into disarray the already struggling process of negotiations with the insurgents. Another topic of discussion at the meeting will be how to move forward with peace talks.

A second U.S. official in Kabul played down worries about the gathering.

“There’s probably more concern in Washington, D.C., than here,” said the official, who also spoke on condition of anonymity. “Out here in Afghanistan, we welcome and embrace the jirga. It is an internal Afghan matter, part of an ancient tradition of consensus building.”

Special correspondent Javed Hamdard in Kabul contributed to this report.