Jeff Zeleny and Marc Santora have a good article up in The New York Times about how "Even as they call for an end to the war and pledge to bring the troops home, the Democratic presidential candidates are setting out positions that could leave the United States engaged in Iraq for years." Specifically:
John Edwards, the former North Carolina senator, would keep troops in the country to intervene in an Iraqi genocide and be prepared for military action if violence spills into other countries. Senator Hillary Rodham Clinton of New York would leave residual forces to fight terrorism and to stabilize the Kurdish region in the north. And Senator Barack Obama of Illinois would leave a military presence of as-yet unspecified size in Iraq to provide security for American personnel, fight terrorism and train Iraqis.
One way to look at this is to try to decide who has the least-bad plan here. A better way to look at it is that the situation on the ground is evolving, the candidates are all being vague, and it's more important to build the strength of certain ideas in hopes of shifting the entire debate further in the direction of complete withdrawal. The problem with all of these plans is simply that they won't work. It'll be untenable to keep small numbers of troops stationed in the country in the way the candidates' rhetoric seems to envision. What they're saying they'll do will either result in us going back to a big (80,000-100,000 or more) force or else down to essentially zero.
The correct answer is essentially zero. The candidates all realize that the status quo is untenable, but can't seem to bring themselves to see that the alternative to the status quo is to leave and let Iraq's fate be determined by the Iraqis.