Afghan elders at a grand assembly in Kabul have called for a security deal with the US to be signed this year.
The pact allows thousands of US troops to remain in Afghanistan once combat operations end in 2014.
But President Hamid Karzai, who wants to delay the deal, told delegates he would only sign it once the US had brought peace to his country.
The US has said it is neither “practical nor possible” to delay the signing.
The Bilateral Security Agreement also has to be approved by the Afghan parliament.
The deal under discussion may see 15,000 foreign troops remain after 2014, although the US says it has not yet taken a decision on any presence.
The soldiers who stay beyond 2014, when most foreign combat forces leave, would primarily train and mentor Afghan forces. Some special forces would stay to conduct “counter-terror operations”.
More than 2,000 elders have been taking part in the grand assembly of elders, or Loya Jirga, meeting behind closed doors in Kabul for the past four days.
“Given the current situation in, and Afghanistan’s need… the contents of this agreement as a whole is endorsed by the members of this Loya Jirga,” a declaration reached at the end of the meeting said, quoted by AFP news agency.
“The Loya Jirga requests the president to sign the agreement before the end of 2013.”
Opening the meeting on Thursday, the Afghan president urged delegates to support the pact, but said he would not sign it until after the election scheduled for April 2014.
The BBC’s Karen Allen, in Kabul, says the vast majority of elders wanted the deal signed within a month.
The assembly’s chairman, Sibghatullah Mojaddedi, said he will resign his official posts and leave the country if the security deal is not signed by the end of the year.
The past few days have seen tense diplomatic telephone exchanges between US Secretary of State John Kerry and President Karzai, our correspondent says.
Washington insists the deal – which has taken months to negotiate – must be signed before the end of this year in order to secure plans for how many troops will remain in Afghanistan beyond 2014.
State department spokeswoman Jen Psaki said: “We believe that signing sooner rather than later is essential to give Afghans certainty about their future before the upcoming elections, and enable the United States and other partners to plan for US presence after 2014.
“It is neither practical nor possible for us to further delay because of the uncertainty it would create.”
Security has been tight for the meeting after a suicide bombing last weekend near the huge tent where it is being held.
The Taliban has branded the meeting a US-designed plot, and has vowed to pursue and punish its delegates as traitors if they approve the deal.