State Department officials said Tuesday that formal negotiations to extend U.S. troop presence in Afghanistan past 2014 are set to begin soon — contradicting claims by Vice President Joe Biden that U.S. troops will be "leaving in 2014, period."

Biden emphasized in last week's vice presidential debate that U.S. troops would exit the country in 2014.

"We are leaving in 2014, period, and in the process, we're going to be saving over the next 10 years another $800 billion," he said.

U.S. negotiators met last week in Kabul with their Afghan counterparts to discuss the Bilateral Security Agrement, Foreign Policy's Josh Rogin reports:

Marc Grossman, the State Department's special representative for Afghanistan and Pakistan, explained today that's not the whole story. Grossman said Tuesday that the point of the upcoming negotiations is to agree on an extension of the U.S. troop presence well past 2014, for the purposes of conducting counterterrorism operations and training and advising the Afghan security forces. […] Some U.S. military officials have said the plan is to keep 25,000 American troops in Afghanistan past 2014, but Grossman insisted that there is no number yet and the 25,000 figure quoted in reports is speculative. NATO announced Monday that it will also keep international troops in Afghanistan past 2014 alongside U.S. troops, not for combat but strictly for the mission of training and advising the Afghans.

This makes the third Biden debate claim the administration or campaign has since walked back or clarified.

The vice president suggested President Obama's tax plan would only raise taxes on individuals earning more than $1 million in income — rather than the $250,000 threshold the administration has pushed all year. The campaign quickly shot down the claim the next day.

White House press secretary Jay Carney defended Biden's insistence that "we weren't told" about the requests for more security at the U.S. Consulate in Benghazi, but clarified that Biden was only speaking for himself and the president.