“After the Soviets left [Afghanistan], the US made a mistake,” said Mr Gates. “We neglected Afghanistan and extremism took control of that country, and the US paid a price for that on September 11, 2001. We won’t make that mistake again."
Substitute "Iraq" for "Afghanistan" in the above, and make the appropriate changes to the tenses of the verbs, and you get why we're not leaving Iraq.
If you're not now convinced of the wisdom or necessity of staying in Iraq, you had better find a way to get used to it. Most Democrat politicians are pandering their way into positions that support, in one way or another, a retreat (or "redeployment" if you buy into it) from Iraq. But just because the D's now can do nothing except run against everything that Bush has done, doesn't mean that they will leave Iraq. Whichever D gets elected (God forbid), they'll find a way to stay in Iraq. Retreat ain't gonna happen. It is the same mistake Gates spoke of.