Updated

KABUL, Afghanistan -- Despite Taliban threats, about 2,000 Afghan elders will convene this week as President Hamid Karzai seeks support for a security partnership with the U.S. after the scheduled withdrawal of international troops by the end of 2014.

The loya jirga, or grand council, could give Karzai political cover for negotiations over a deal to keep some American troops in Afghanistan for another decade despite opposition from his people and the war-weary U.S. public.

Karzai has set out terms for a possible partnership -- such as banning international troops from entering any Afghan home and taking control of all detention facilities almost immediately -- that have so far been unacceptable to American officials, according to people familiar with the discussions.

The roughly 100,000 U.S. troops currently in Afghanistan operate without any bilateral agreement governing their actions.

In Washington, U.S. State Department spokesman Mark Toner said discussions were ongoing with the Afghan government.

"We want an agreement that's in the best interest of both our countries," Toner said. "It's better to get it right rather than fast."

Karzai has repeatedly vacillated between criticizing the U.S. for acting unilaterally in Afghanistan and praising his American allies as brothers in arms against the Taliban. It has been difficult to tell in recent months if he is just trying to stoke populist support with his criticism or is really preparing to stand firm on what he sees as a violation of sovereignty.

Few expect the four-day loya jirga, which begins Wednesday, to produce much of substance, both because its legal status is unclear and because there is no draft accord to present to the assembled elders.

Parliamentarians say the meeting is unconstitutional because it sidelines the legislature, which should be the body to decide national issues.

"The real representatives of the people are in parliament. We have been elected. The jirga delegates have only been selected by the administration," said Nasrullah Sadiqizada Nili, a lawmaker from Day Kundi province. Although parliamentarians have been invited, Nili said he and many others would not attend in protest.

"This loya jirga has no legitimacy," Nili said.

Karzai's former presidential challenger, Abdullah Abdullah, ridiculed the idea of Karzai's hand-picking a group of people to represent a national consensus. He said that even the idea of "tribal elder" had been bent to political aims, noting that he was invited as a "dignitary from the Panjshir tribe" though he has no position of leadership in a tribe.

He went on to warn that if people accept this jirga as legal, Karzai could easily call another to try to amend the constitution so that he can run for a third term as president.

"Holding this jirga is illegal. It is against our country's constitution. The goals and aims are confusing. This jirga has hidden goals and whatever decisions are made in this jirga are not acceptable," Abdullah told reporters Sunday.

A spokesman for the meeting said there are no such ulterior motives and that Karzai is simply hoping to get input from a wider cross-section of Afghanistan than that which is represented in parliament.

"This is just the government asking the people their point of view, what they think about whether we should sign a contract with the United States or not," Safiullah Zeer said. He noted that the meeting has been dubbed an advisory loya jirga, to make clear that it does not have any authority to make decisions. He said any partnership agreement will have to be approved by parliament before it becomes binding.

Toner, the State Department spokesman, called the loya jirga "a traditional way for the Afghans to talk about many issues, and we support it. And you know, we believe that it's going to lead to a reaffirmation of our strong alliance with Afghanistan."

The 2,030 delegates will form some 40 committees to discuss issues involving the partnership, along with possibilities for peace with the Taliban, Zeer said.

The Taliban have condemned the meeting as an attempt by the U.S. to justify a permanent presence in Afghanistan, promising to launch attacks to disrupt it.

The U.S. "will practice absolute freedom, will not abide by any Afghan stipulations and will continue its military operations and presence as long as it wants," the Taliban said in a statement issued Monday.

The insurgent group also claimed to have obtained a copy of security plans for the conference and said it would use the plans to attack the meeting. The Afghan government and NATO forces said the document, posted on the Taliban's website, was a forgery.

Much of Kabul went into a security lockdown ahead of the meeting, with extra roads closed and intelligence agents swarming around the meeting hall on the outskirts of the city. At the last such meeting -- a "peace jirga" held last June -- Taliban insurgents fired into the tent, disrupting the gathering but causing no casualties. Since then, a new hardened structure has been built that should in theory be less vulnerable to incoming fire.