Obama could also announce a timetable for recalling the 20,000 other troops he ordered to Afghanistan as part of his December 2009 decision to send reinforcements to reverse the Taliban's battlefield momentum. The official spoke on condition of anonymity in order to discuss the plans before Obama's formal announcement. .

Obama spokesman Jay Carney said Tuesday that the president had finalized his decision on the withdrawal plan and would address the nation from the White House at 8 p.m. Wednesday. He said the president informed his national security team of his plans during a White House meeting Tuesday morning.

While Carney would not discuss the details of Obama's decision, he said the drawdown set to begin next month puts the U.S. on a path toward giving Afghans control of their own security by 2014.

A reduction this year totaling 10,000 troops would be the rough equivalent of two brigades, which are the main building blocks of an Army division. It's not clear whether Obama's decision would require the Pentagon to pull out two full brigades or, instead, a collection of smaller combat and support units with an equivalent number of troops.