The debate over Iraq has really become two debates. One is about the past--whether President Bush's troop surge was the right policy. The other is about the future--whether the United States should embrace a timetable for withdrawing combat troops.

Barack Obama, the presumptive Democratic nominee, says that the security situation in Iraq has improved. He declared on July 15, "Our troops have performed brilliantly in lowering the level of violence." But on ABC News he contended that the troop buildup was not the whole story: "The political dynamic shifted at the same time that our troops did outstanding work."

Republicans think they have Obama cornered. Former New York City Mayor Rudy Giuliani said on CNN, "It [seems to me] he would admit he made a mistake in not supporting the surge." He doesn't. Asked by ABC News whether he would have backed the surge if he had known then what he does now, Obama answered no.

He argues that the troop buildup has been costly ("over $10 billion each month," he said on July 15); distracting ("In the 18 months since the surge began, the situation in Afghanistan has deteriorated"); and limited in its achievements ("Iraq's leaders have not made the political progress that was the purpose of the surge").

John McCain's argument is, essentially, I told you so. "[Obama] was wrong then. He is wrong now. And he still fails to acknowledge that the surge has succeeded," the presumptive Republican presidential nominee said during a town hall meeting in New Hampshire last week.

Obama wants to shift the argument from a debate about the past--who was right about the surge--to a debate about the future--what the U.S. should do now. "For weeks now," Obama said before leaving for the Middle East, "Senator McCain has argued that the gains of the surge mean that I should change my commitment to end the war."

Over the past year, a greater share of Americans have come to believe that the U.S. military is making Iraq more secure. Those who agree that "the U.S. military is making progress in improving conditions in Iraq and bringing an end to violence in that country" rose from 47 percent in August 2007, to 52 percent in February 2008, to 54 percent in June, according to CNN/Opinion Research polls.

Has the impression of military progress increased public support for the war? No. The number of Americans who favor the war has hardly changed: 31 percent in January 2007, when the troop buildup began, and 30 percent this June. Two-thirds of the public continues to oppose the war--progress or no progress. Most Americans just want the war over.

McCain may be undermining his own argument for staying in Iraq when he says, as he did last week, "This strategy is not succeeding; it has succeeded." Conservative columnist Jonah Goldberg recently wrote in the Los Angeles Times, "The more the surge succeeds, the more politically advantageous it is for Obama. Voters don't care about the surge; they care about the war."

When the Iraqi government handed Obama crucial support for his withdrawal plan, he said in Jordan, "I welcome the growing consensus in the United States and Iraq for a timeline." Even McCain caught himself saying in a CNN interview, "I think it's a pretty good timetable," before quickly adding that any withdrawal should be "based on conditions on the ground."

On the issue of what to do now, Obama thinks he has McCain cornered: If things are so much better in Iraq, why doesn't McCain want to get U.S. troops out?

McCain had one final card to play, and he played it last week while Obama was overseas. "An unconditional withdrawal without paying attention to the facts on the ground could lead to our failure, a resurgence by our enemies, and we would have to go back," McCain said in Pennsylvania. "My friends, when I'm president of the United States, we will come home. We will come home with victory and honor, but we will never have to go back, because we will have won this conflict."

McCain's message? You want to end this war so that the U.S. can stay out of Iraq? I'm your man.

This article appeared in the Saturday, August 2, 2008 edition of National Journal.

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