The Obama administration has decided to de-emphasize plans to begin withdrawing US forces from Afghanistan starting July 2011, administration and military officials said Tuesday.

The new policy is to be unveiled at a NATO conference in Lisbon next week, where the United States and other NATO countries are set to discuss their commitment to Afghanistan. The United States hopes to introduce a plan to begin the withdrawal of military forces from Afghanistan by 2014, senior officials told McClatchy.

Afghan forces should be able to operate independently of foreign troops and secure the country by 2014, President Hamid Karzai said at a conference in the Afghan capital.

"We think that NATO, in the collective sense, and other countries, that include the United States, will move to establish and define an enduring commitment, enduring partnerships with Afghanistan," an official told AFP.

President Barack Obama announced July 2011 as the date the United States would begin withdrawing troops from Afghanistan last year, after sending an additional 30,000 US troops to the region as part of his surge strategy.

Presently, there are over 150,000 US and international troops in Afghanistan.

In August, a spokesman for the White House suggested that the number of troops withdrawn on the July 2011 deadline would be based on the amount of progress made in Afghanistan.

"Obviously the scope and rate of withdrawal will be conditions-based, but the date is not negotiable," he said.

The president is now de-emphasizing the 2011 deadline because conditions in Afghanistan are unlikely to allow for a speedy withdrawal, an official told McClatchy.

"During our assessments, we looked at if we continue to move forward at this pace, how long before we can fully transition to the Afghans?" said a senior administration official. "And we found that we cannot fully transition to the Afghans by July 2011. So we felt we couldn't focus on July 2011 but the period it will take to make the full transition."

United States Central Command, which oversees military operations in Afghanistan, has not submitted any troop withdrawal order for the July deadline.

"With the exception of the Dutch and Canadians, no country has said they'll leave Afghanistan," an official told CNN. "The British have said they'll end combat operations by 2014. But the strategy is designed so that, hopefully, we don't have to be in a combat situation at that time."

Republicans have been vocal critics of the July 2011 deadline.

"It was purely a political decision, not one based on facts on the ground, not one based on military strategy," Republican Senator John McCain said on NBC's Meet the Press.

Although General David Petraeus voiced support for the July 2011 drawdown, retiring General James Conway said the deadline is "probably giving our enemy sustenance."

"In fact we've intercepted communications that say, 'Hey, you know, we only need to hold out for so long,'" he said.

With the Republican victories in the recent midterm elections, Obama is facing less pressure to begin withdrawing troops from Afghanistan. Democrats in Congress threatened to cut off funding for the war in Afghanistan earlier this year, but any cuts in military funding are unlikely with a Republican majority in the House of Representatives.

Even after US and NATO forces withdraw from Afghanistan, the country will still rely on Western aid for supplies and funding, officials warn.

"Sustainment is going to be a key issue," one official said. "The only way Afghan forces CAN be sustained over time is with foreign assistance."