He likely wouldn't be able to get foreign troops from European countries. Or as many as originally thought.
He'd have a steady withdrawal from Iraq until 2006 when Muslim fratricide and the risk of a civil war hit high levels.
If steady withdrawal delays death of Zarqawi than the conflict would be having a huge negative downward pressure on his approvals, especially if Zarqawi gets promoted within Al Qaeda's ranks.
Therefore he would start the surge of 07-08 and lose reelection to McCain, most likely, who would keep us in for the remainder of his term.