John McCain will be pushing the line that the "surge has worked," based on declines in attacks on US troops and declines in violence in Baghdad and al-Anbar Province, even as violence is again on the increase in some other parts of Iraq, and basic political and economic settlements remain unachieved. The problem is that neither of these declines in violence has had very much to do with an increase in the presence of US troops, although the case is stronger for Baghdad than for al-Anbar. In Baghdad the decline in violence would ultimately have happened because the main source of it was ethnic cleansing and the rise of sectarian segregation. This is now basically complete, with few integrated neighborhoods left and with many Sunnis fleeing both Baghdad and Iraq. A city that was 2/3 Shi'i, is now about 3/4 Shi'i, with the US effectively aiding this outcome.
The turning of tribal sheikhs against al-Qaeda in Iraq in al-Anbar Province has had nothing to do with increased US troops (although providing arms probably helped) and everything to do with al-Qaeda in Iraq stupidly killing sons of some of those sheikhs. Ironically, one of the biggest neocon hawks, Charles Krauthammer, has effectively admitted this. He criticized Dems in Congress for saying the 2006 election changed things by pointing out that this change of attitude had happened prior to the election, even as McCain and crew are claiming it came later in 2007 with the US troop surge. Not so. Bottom line is that the violence situation has been naturally self-stabilizing, making it much easier to engage in large-scale withdrawals of US troops without destabilizing Iraq beyond what it is anyway.