In the interests of a political detente, maybe Barack Obama should admit that he was wrong about the '07 troop surge in Iraq, and John McCain should admit that he was wrong about the '02 decision to invade. But since neither candidate is likely to budge, perhaps the big question for voters should be: In hindsight, whose misjudgment was worse?

On his global tour, Obama has employed all sorts of artful verbal constructs in order to avoid addressing his previous pessimism about the troop hike. (Obama in January '07: "I am not persuaded that 20,000 additional troops in Iraq is going to solve the sectarian violence there. In fact, I think it will do the reverse." Obama in July '07: "The surge has not worked." And Obama in November '07: "We're actually worsening, potentially, a situation there.") For instance, while he told CBS News the other night that, yes, "our U.S. troops have contributed to a reduction in violence," he nevertheless parried the question of whether the reduction would have occurred without the surge. He replied, "I have no idea what would have happened...So this is all hypotheticals."

As for McCain, hardly anyone - aside from the occasional town-hall questioner - bothers to ask him anymore whether he has any second thoughts about marching to war as a Bush cheerleader. (McCain, September, 24, 2002: "I believe the success will be fairly easy." McCain, five days later: "I believe that we can win an overwhelming victory in a very short period of time." McCain, March 24, 2003: Once the Saddam forces are gone, "we will be welcomed as liberators.") He never raised a whit of protest when war fever was high, and, of course, he has no second thoughts today. He still refers to Iraq as the central front in the war on terror, and he still talks about "victory" without defining what he means.

The difference is that one guy was wrong about a tactic. The other guy was wrong about a fundamental national security decision.

McCain, naturally, wants the electorate to focus exclusively on the surge. And, yes, as it turns out, he was basically right about the surge (while overstating its prowess, as we shall see in a moment). But the surge, lest we forget, was basically a last-ditch tactic that was designed to mitigate a national security disaster, to get the conflagration under control. McCain was an early, unquestioning enabler of the invasion that sparked the conflagration. He helped set the whole house on fire (at a cost thus far of 4125 American lives and half a trillion dollars), yet now he wants to be reap political reward from the fact that he helped hose down some of the flames.

Nor does McCain talk much about some of the other factors, often cited by U.S. intelligence and military sources, that have contributed to the lessening of violence - such as the Shiite militia cease-fire, and the growing opposition, among Sunni tribal leaders, to the insurgents who fight in the name of al Qaeda. Indeed, the Sunni revolt against al Qaeda (commonly called "the awakening"), began in Iraq's Anbar province in autumn '06 - roughly four months before President Bush even announced his decision to hike the troop levels.

And by the way, take note of that accurate Sunni timeline - because McCain got his facts confused again late yesterday, when he mangled the timeline. (McCain has been factually confused a lot lately, as the Washington press corps is finally acknowledging.) According to the transcript of a CBS News interview, McCain credited the surge with sparking the awakening. In his words, "because of the surge, we were able to go out and protect (the Sunni shieks). And it began the Anbar awakening. I mean, that's just a matter of history."

Maybe in his mind it is, but not in factual reality world. The U.S. military spoke publicly about Sunni leaders' revolt against the insurgents long before the surge. In a press briefing on Sept. 29, 2006, Col. Sean McFarland said that the insurgents had been doing well earlier in the year, but "this is a different phenomena that's going on right now...The tribal leaders are stepping forward and cooperating with the Iraqi security forces against al Qaeda, and it's had a very different result. I think al Qaeda has been pushed up against the ropes by this."

Fortunately for McCain, his latest confusion of the facts did not actually air on TV; it surfaced only in the transcript. And even if it had aired, most Americans are not conoisseurs of the Iraqi timeline, so McCain would have gotten away with it anyway. More important, long term, is the question I posed at the outset. Will swing voters ultimately decide that Obama's erroneous stance on the surge tactic is worse than McCain's erroneous stance on the war itself, or vice versa?

But, short term, what probably matters most are the pictures. Which image was more potent on TV early this week: Obama striding with Middle East leaders on a rooftop in Jordan - or McCain trundling in a golf cart with octogenarian George H. W. Bush? Those Republican strategists who perfected their craft during the Reagan era must be tearing out whatever hair they still have.