Today John McCain was arguing that the Democratic Party should be happy with the position of General Petraeus that "the surge" is working and that there will (possibly) be a "reduction" in troop levels to pre-surge levels in about a year. It's not such a bad talking point, but beyond that isn't very coherent.
A "surge" has to end, or it is an "escalation". It was thus a foregone conclusion that if we were going to keep calling this a "surge" it would have an ending point.
If "the surge" ends with no political progress, there is no reason to believe that further troop withdrawals are possible or even advisable if you wish to even maintain the status quo.
The military successes of "the surge" do not automatically translate into political success. If "the surge" brings about none of the political reforms and improvements promised at its inception, the surge can be an unqualified military success yet still be a political failure. (Surely McCain has heard reference to armed conflicts were "we won every battle, yet lost the war".)
I would venture that it is because he continues to expect that number of troops to remain in the field for at least another five to ten years.
Whatever "points" the Democratic Party can claim for getting tentative dates for the end of the surge, maintaining pre-surge troop levels for the indefinite future does nothing to bring this conflict to an end. McCain knows that, and if he wishes to vindicate himself as a "straight shooter" he should admit as much. (But perhaps "McCain the straight shooter" was always more of a matter of perception than reality.)