"If you say there's a date certain for withdrawal, your friends and enemies who will be in the region make accommodations accordingly," McCain said.
During Tuesday night's prime time address laying out his Afghanistan troop buildup, President Obama said that a troop withdrawal could begin as early as July 2011.
McCain said Wednesday in an interview on CNN's American Morning that Obama "gave an excellent speech and I think the policy, although it's very extended period of deliberation which is now behind us, is a good one, and I'm confident the president will do exactly as he says."
But the Republican senator from Arizona criticized the president's comments regarding an exit strategy, adding that "it's contradictory to say you're going to have your withdrawal dictated by the situation on the ground, and at the same time say that there's going to about date certain for withdrawal."
McCain challenged the president hours before Obama addressed the nation on his new Afghanistan strategy. The president and members of his war council spent about an hour briefing senior members of Congress at a White House meeting that multiple sources described as businesslike and sobering. Democratic and Republican lawmakers, who attended the meeting, said Obama laid out his plans to escalate the military mission before several lawmakers asked questions.
Three GOP sources told CNN that Sen. John McCain used the meeting to directly challenge the president on his exit strategy. The sources said that Senate Minority Leader Mitch McConnell deferred to McCain, who questioned the concept of announcing now plans to begin withdrawing in July, 2011. These sources said the president responded to McCain by promising that the withdrawal would be based on conditions on the ground.
McCain also says he has problems with the administration's civilian strategy in Afghanistan.
"Another concern I have has to do with the civilian side of our counterinsurgency strategy," said McCain in his opening statement at a Senate Armed Services Committee hearing Wednesday morning on Afghanistan. Secretary of State Hillary Clinton, Defense Secretary Robert Gates, and Adm. Michael Mullen, chairman of the Joint Chiefs of Staff, were among the witnesses at the hearing.
McCain, the ranking Republican on the committee, said "I am concerned that we and our allies do not have a unified plan to 'build' – to work with and support our Afghan partners, in Kabul and beyond, as they build their own nation, their own economy, and their own free institutions. I'm also concerned by reports of divisions in our embassy, and by major differences between our commander and our ambassador."
In his speech at West Point Tuesday night, Obama declared that the U.S. " will work with our partners, the United Nations, and the Afghan people to pursue a more effective civilian strategy, so that the government can take advantage of improved security. This effort must be based on performance. The days of providing a blank check are over."
–CNN's Paul Steinhauser contributed to this report.
Follow Paul Steinhauser on Twitter: @psteinhausercnn