If the surge were a success, Mc Cain and Bush would be bringing home the troops. The fact that McCain and Bush want to keep the surge in place means the surge is a failure. The need to keep the surge means there is a need to keep Iraq from falling apart. If Iraq will fall apart without the surge, then the surge has failed. Until the surge is not needed the surge is failing. If a surge in troops does not stabilize Iraq enough for the surge troops to go home, then there is no point in keeping them in Iraq.
If there were the possibility of the disparate forces in Iraq coming together, these forces would be taking advantage of the presence of American troops. That is not happening. Sharing power is not on the agenda for any of the players in Iraqi politics. All sides are planning to wage war on each other once the Americans go home. The surge is only wasting lives, money and resources by suppressing an inevitably violent struggle for control of Iraq. Let the Iraqis create their own future. And let Bush get the credit for whatever results.