20th
No candidate left behind.
If you count every battleground state where Obama is UP by 4% or less as a McCain win, Obama still wins the electoral vote 273-265. This means that even if Ohio, Florida, Virginia, North Carolina, Nevada, Missouri, and North Dakota all go for McCain, he will still lose the race.This is a more pro-McCain accounting than even Karl Rove is giving at Rove.com.
If McCain can flip Colorado or New Mexico, currently at 7% and 8% in favor of Obama respectively, then he would win.
Try the math yourself at the CNN Electoral Calculator.
Update: It seems to break out like this: If McCain loses Ohio, Virginia, North Carolina, or Florida - any of them - then he absolutely must win Nevada, New Mexico, and Colorado to win. This is still with the very ‘conservative’ assumption that McCain wins ALL states that are currently 4% or more for Obama. This is an unlikely scenario but it is most reasonable path.
A single terrorist attack of enough import to dominate 2 - 4 days of the news cycle would be enough to drag the media consciousness back over to national security issues where McCain has better polling traction. Osama bin Laden distributed a threatening video to the West priot to the Bush-Kerry general election that gained 6% for Bush.
