I can't tell from here who will be the Democrat nominee, both Obama and Clinton are certainly excellent prospects.
However, George W. Bush's blunders have killed over 4000 Americans, we've p-issed away trillions of dollars, the national debt has doubled under his administration, countless people are losing their homes, fuel costs have doubled and on their way to triple what they were since Bush took office, food shortages have appeared in the last few months, wages aren't keeping up with inflation, Bush is well on his way to delivering The Great Depression II ... and the list goes on. Al Qaeda hasn't damaged us to the degree George W. Bush and the Republican leaders in Congress have damaged us.
And John McCain as Republican nominee offers more of the same in the form of George W. Bush's third term. How do you think that's going to work out for him? He may as well use "Heckuva Job, Bushie" as his campaign theme.