Washington (CNN) -- A new report questions whether the centerpiece of the Obama administration's exit strategy for Afghanistan -- a training program for Afghan security forces -- can deliver as promised.
The United States says that it will gradually hand off responsibilities to Afghanistan security forces as it draws down U.S. troops between this summer and the end of 2014.
Sen. Carl Levin, chairman of the Senate Armed Services Committee, earlier this week called for an even larger Afghan army, which would make the handoff more of a challenge.
And the special inspector general for Afghanistan reconstruction issued a separate warning that the infrastructure for the Afghan forces -- bases, training facilities, barracks -- may not be in place in time and that the Afghanistan government may be unable to keep them operating.
But the latest concerns came Thursday, with the release of a report questioning whether there are enough people to train the Afghan forces.
"Of particular concern is the ongoing shortfall in coalition training personnel, which continues to hamper the ANA's (Afghan National Army's) ability to acquire skills it needs to become less dependent on coalition forces and begin assuming lead responsibility for Afghanistan's security," the report says. "Until this shortfall is addressed, the ability of the ANA to develop necessary capabilities will remain at risk."
The Government Accountability Office report is titled "Afghan Security: Afghan Army Growing but Additional Trainers Needed; Long-Term Costs Not Determined."
It says the Afghan army is plagued by problems of attrition and literacy.
The Accountability Office also questioned when the Afghanistan government will be able to take on the costs of its own security forces. "Due to the Afghan government's limited financial resources, international backing of the ANA will be needed for years to come -- at least a decade, by some estimates -- if the current course is to be maintained," the report says.
Similar cautions were put forward Monday by the special inspector general for Afghan reconstruction, retired Marine Gen. Arnold Fields.
He said billions of U.S. taxpayer dollars may be wasted because the United States lacks a comprehensive plan for the buildup of the Afghan Army. He added that hundreds of building projects for Afghan security forces are behind schedule.
And on Tuesday, Sen. Carl Levin, D-Michigan, said he was urging the White House to expand the Afghan army and police more than had been planned previously.
"We believe that proposed increase and the size and capability of the Afghan forces is a key part of our ticket to success in Afghanistan, of the mission that we have there, and is also critically important to the faster reduction of American forces from Afghanistan, which will begin in July of this year," Levin said at a Capitol Hill news conference.