President Hamid Karzai is facing a growing backlash from Afghan political leaders over his reluctance to sign a long-term security agreement with the United States.

Karzai had appeared to reach an agreement last week that would permit up to 15,000 foreign troops to remain in Afghanistan after the formal end of U.S. combat operations in 2014. But Karzai has since refused to sign the accord until the U.S. government agrees to a series of escalating demands.

With the Obama administration insisting that it will prepare for a full withdrawal if the agreement is not signed by year’s end, Afghan political leaders are increasingly nervous that the country’s fledgling armed forces could be on their own after 2014. If the agreement is not concluded, Afghanistan could also lose $4 billion in annual aid for its military.

“If he doesn’t sign, Afghanistan will go to civil war and Karzai will be responsible,” said Moeen Marastial, a former member of parliament who previously served in Karzai’s government. “Not only military commanders but ordinary people know, if this agreement is not signed, and there is no support and training for the military, the soldiers won’t be able to feed their families.”

Few Afghan leaders and analysts had expected Karzai to dig in so strongly over the accord, especially after an influential council of tribal leaders and civic activists urged him this week to sign it.

Now that he has laid out additional demands — including that the U.S. government release all 17 Afghans being held at the Guantanamo Bay detention center in Cuba — Karzai is facing criticism that his actions are being driven by personal grudges and paranoia.

The Americans should know that “the Afghans are not with President Karzai anymore,” said Ahmad Saedi, a Kabul-based political analyst.

Political leaders and analysts in Kabul have various theories about why Karzai is holding out, including that he is facing pressure from Iran or wants to win U.S. support for his favored candidate in the presidential election next spring.

Many analysts and political leaders believe that Karzai is overestimating the will of the Obama administration to continue the negotiations.

“There are high and growing levels of concern in Afghan society over the durability of the international commitment, and there are high and growing levels of concern in the international community, to include the American public, about whether we’re really wanted,” James Dobbins, Obama’s special envoy to Afghanistan and Pakistan, said in an interview.

During a meeting with U.S. national security adviser Susan E. Rice on Monday night, Karzai said he would sign the agreement only after he’s convinced that no more U.S. soldiers would enter Afghan homes uninvited — a reference to nighttime anti-terrorism raids — and that the Obama administration would help launch peace talks between his government and Taliban insurgents.

To help start that peace process, Karzai requested the release of the Afghan prisoners at Guantanamo Bay.

By Wednesday, there were signs Karzai might be softening his demands. In an interview with Radio Free Europe, he reiterated his call for an end to U.S. troop raids on Afghan homes and the start of peace talks, but didn’t mention the prisoner issue.

“Whenever the Americans meet these two demands of mine, I am ready to sign the agreement,” Karzai said.

On Wednesday night, Karzai spokesman Aimal Faizi insisted that the president wasn’t giving up on the prisoner issue, saying it was part of his call for an American-led peace process.

Obama officials have said they are not willing to reopen negotiations with Karzai, noting that the agreement was finalized after a year of discussions. And they say they need a completed accord soon to be able to plan a post-2014 presence, focused on anti-terrorism operations and training the Afghan military. But some U.S. officials say they are willing to give Karzai more time and remain hopeful he will buckle under domestic political pressure.

“Militaries have to plan, and you can’t just have a last-minute deal, but I think there is a bit more flexibility than these arbitrary dates that have been set” by the U.S. side, said Linda Robinson, a Rand Corp. senior international affairs specialist who recently wrote a book on U.S. Special Operations missions in Afghanistan.

But Ali Ahmad Jalali, an Afghan American who served under Karzai during the early years of his administration, said the pressure on Karzai is “building within the government, within the society and within the elites of Afghanistan.”

“People are confused, and are calling on the international community not to sacrifice the future of Afghanistan for one man,” he said.

Karen DeYoung in Washington and Sayed Salahuddin in Kabul contributed to this report.