"We need a fundamental... reassessment as to whether this broad counterinsurgency effort makes sense," Chandrasekaran told moderator John Dickerson.
The Washington Post obtained a confidential report in which McChrystal said that without additional forces, the war against insurgents in Afghanistan will end in failure.
However, "the landscape here has fundamentally changed" since McChrystal was asked in June to draw up an assessment on the situation in Afghanistan, Chandrasekaran said.
On Sunday, Mr. Obama told "Face the Nation" host Bob Schieffer that he is not yet considering a troop increase because he has not received a request for one. Now that the report has been made public, however, it "could curtail his ability to make a decision in the timeframe he wants," CBS News' Chief Political Consultant Marc Ambinder told Dickerson.
"There's no question this is more risky than it was for the White House last week," he said.
Initially, the Obama administration's strategy was to dismantle and destroy al Qaeda in Afghanistan through a comprehensive civilian counterinsurgency effort. In recent months, however, the mission has come up against a general election that was perceived as largely fraudulent, growing doubts on Capitol Hill, policy issues like health care that have distracted the White House, and disintegrating public support.
Chandrasekaran explained that some think Mr. Obama should abandon the broad counterinsurgency efforts in favor of a narrower approach against al Qaeda using predator drones and special forces on the ground.
"Trying to set up a strong national government is a path that's perhaps way too unattainable," he said.
Whatever the president decides to do, the president "will find himself in a politically volatile position," Chandrasekaran said, with Democrats supporting troop withdrawals and Republicans in favor of following the general's request for more troops.
Ambinder said it is not clear whether liberals will consider the Mr. Obama's actions on Afghanistan as critical as his commitment to health care reform, particularly to liberal elements of reform like a government-run health care option.
"They're willing to give him -- not a pass -- but some time" to make a decision on the war, Ambinder said.
"As the months go by, as troops from Iraq are repurposed to Afghanistan, then the debate might polarize and Obama might have to make that choice. I think he thinks he has a couple of months before he really has to make that choice."
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