8 years of poor leadership, ongoing efforts to divide the country ideologically, incompetent conduct of foreign policy resulting in the alienation of many if not most of our major allies, use of torture, horrific response to Katrina, and the list goes on.
Add the fact that McCain's positions in the campaign so far don't indicate that he is trying to significantly differentiate himself from the Bush Administration.
Finally, a candidate who is committed to restoring the image of America around the world through a more thoughtful foreign policy, providing affordable health care to most if not all Americans, a commitment to Medicare, Medicaid and Social Security rather than attempts to dismantle or privatize them, an energy policy that will do more than just advocate more drilling for oil, and the opportunity to elect the first African-American president in US history.
Just trying to come at this from a positive perspective rather than enumerating why the Dems might manage to wrest defeat from the jaws of victory.