Jen Rubin thinks there is one reason:

There are many reasons, but I would suggest an overriding one: the surge. Without McCain’s determination on the surge and its resulting success, the race would look quite different. In that effort, McCain did show his personal characteristics (tenacity and bravery, most clearly) and many Republicans, conservatives included, came to see him as a warrior in the toughest policy battle in recent memory. It was the means by which he distinguished himself from his competition and by which he could appeal to skeptics who came to see his past policy heresies in greater perspective. (Or it could just be that the competition was very, very weak.)

I think she's right that his bravery and honesty are indeed signs of a remarkable character. The question, however, is still in front of us, and is currently unknowable: What if McCain was brave but still wrong last spring? Yes, the surge did much better in stabilizing Iraq than Petraeus's metrics predicted. But we still do not know for sure why. We are not able to judge yet whether the extra troops were the key; or whether it was the switcheroo of the Sunni tribes; or the strange passivity of the Sadrite militias; or exhaustion; or Iran's self-interest; or what exactly. I'm not sure even Petraeus knows for sure.

What we do know is that the basis for a serious and lasting political settlement in Iraq does not exist and has not come appreciably closer under the surge. Since this was the declared goal of the action, and since we all agree such a reconciliation is critical for an Iraq that will not dissolve into a hot civil war if we leave, we may have simply paused the centrifugal disintegration. We have done so by pushing the military to the brink. I seriously doubt if Bush will withdraw troops below the pre-surge levels before he leaves office. It's not in his nature to take responsibility for his own errors. So McCain might inherit an Iraq in just as rough a shape as 2005, but with the delusion that keeping 130,000 troops in that country is getting us somewhere.

Worse: McCain has signaled that he believes that all those who are skeptical of this strategy are betraying the troops. He has said this time and again - disgracefully, recklessly, and dangerously. Why dangerously? Because if the surge is truly why he is winning the nomination, then his presidency will be wedded to maximalist objectives in Iraq and may even legitimize the notion that withdrawal is some kind of attack on the troops. To have McCain run an anti-Dolchstoss campaign this fall would be a nightmare for a country at war. Maybe his tone will change. Maybe he is privately shrewder about what the surge has - and has not - accomplished. But the current rhetoric is ominous for the country.

(Photo: Alex Wong/Getty.)