Washington ( CNN ) -- President Barack Obama has asked Gen. David Petraeus to replace Gen. Stanley McChrystal as the top U.S. commander in Afghanistan , he said Wednesday . Obama relieved McChrystal of duty over disparaging comments the general 's staff made about top White House officials in an article in Rolling Stone magazine . Petraeus , a counterinsurgency expert , was the architect of the `` surge '' of U.S. forces in Iraq , which some credit with turning the tide of the war . He was promoted to head of the U.S. military 's Central Command in October 2008 by President George W. Bush . Obama said there would be no change in policy as a result of the switch in commanders , but Petraeus and McChrystal have struck different tones in describing the Afghan campaign recently . `` The trajectory in my view has generally been upward , despite the tough losses , despite the setbacks , '' Petraeus told the Senate last week -- a day after fainting while giving testimony . He blamed dehydration when he appeared the next day , June 16 . McChrystal had said just days before that the campaign against the Taliban in Helmand province would take longer than he originally planned . Questioned by the Senate Armed Services committee about the difference in emphasis , Petraeus said : `` The conduct of a counterinsurgency operation is a roller coaster experience ; there are setbacks as well as areas of progress or successes . '' Petraeus will step aside as chief of Central Command to take over as Afghanistan war commander , a senior national security source told CNN 's John King . His appointment to lead the U.S. war effort on the ground in Afghanistan requires Senate confirmation . Senate Armed Services Committee Chairman Carl Levin , D-Michigan , told CNN that he hopes to hold confirmation hearings for Petraeus as early as next week . Obama 's decision to replace McChrystal with Petraeus was `` reasonable , '' Levin said . The chairman of the House Armed Services Committee immediately expressed his support for Obama 's choice . Petraeus `` is the best that we have , '' Rep. Ike Skelton , D-Missouri , said in a written statement . Sen. Jack Reed , D-Rhode Island , called him an `` experienced , thoughtful commander who will step in and provide a continuity of leadership . '' Petraeus all but literally wrote the book on fighting against guerrilla resistance , overseeing the drafting of the Army/Marine Corps Counterinsurgency Field Manual between stints in Iraq . He commanded the 101st Airborne Division , the Screaming Eagles , during the first year of the war in Iraq , according to his official biography on the Central Command website . He then commanded coalition forces and the NATO training mission in Iraq . Petraeus then spent time at Fort Leavenworth , Kansas , working on the counterinsurgency manual before returning to Iraq to take charge of the surge . He holds a doctorate in international relations from Princeton University .
President taps General David Petraeus to replace Gen. Stanley McChrystal in Afghanistan . He was the architect of the ` ` surge '' of American forces in Iraq . He recently said the trajectory in Afghanistan ` ` has generally been upward '' He oversaw the development of the Navy / Marine Corps Joint Field Manual .