The question of the troop escalation’s role on pacifying Iraq has emerged as a critical debate between the two, as the McCain campaign has accused Mr. Obama of failing to acknowledge the success of a strategy that Mr. McCain fervently supported.

The McCain campaign said the troop escalation was a vital component that assured the success of the Awakening movement. And Mr. McCain said Wednesday that when he was referring to the “surge,” he meant the entire counterinsurgency strategy, and not just to the troop escalation that President Bush ordered.

“First of all, a surge is really a counterinsurgency strategy,” Mr. McCain said in Bethlehem, Pa. “And it’s made up of a number of components. And this counterinsurgency was initiated to some degree by Colonel MacFarland in Anbar Province, relatively on his own. And I visited with him in December of 2006. He had already initiated that strategy in Ramadi by going in, and clearing and holding in certain places. That is a counterinsurgency. And he told me at that time that he believed that that strategy, which is quote ‘the surge,’ part of the surge, would be, would be, successful.”

“So then, of course, it was very clear that we needed additional troops in order to carry out this insurgency,” he said. “Prior to that they had been going into places, killing people or not killing people, and then withdrawing. And the new counterinsurgency, the surge, entailed going in and clearing and holding, which Colonel MacFarland had already started doing. And then of course, later on, there were additional troops, and General Petraeus said that the surge would not have worked, and the Anbar Awakening would not have taken place, successfully, if they hadn’t had an increase in the number of troops.”

Conducting a presidential campaign in the middle of a war is somewhat unusual, and several foreign policy experts lament that a great deal of nuance and thoughtful discussion is lost in the political back-and-forth.

If Mr. McCain found himself criticized for seeming to confuse the chronology of events in Iraq, some analysts said Mr. Obama seemed to be giving too little credit to the surge for improving conditions in Iraq. Mr. Obama, who opposed the Iraq war, said in an interview with “Nightline” on ABC this week that if he had to do it all over again, knowing what he knew now, he would still not support the surge.

Mr. O’Hanlon, of the Brookings Institution, said he did not understand why Mr. Obama seemed to want to debate the success of the surge. “Any human being is reluctant to admit a mistake,” he said, noting that it takes on added risk in a political campaign.

And Anthony H. Cordesman, of the Center for Strategic and International Studies, said the political debate did not always illuminate the issues very well. “There are times, I think, where maybe we really ought to step back from this semantic horror show, and remember that this is a political campaign, it is posturing,” Mr. Cordesman said. “Would anyone want either presidential candidate to keep any promise they made today if reality was different in January, or in any point afterwards?”