Romney needs Obama to royally fuck up but he's never done much of that since he started running for president in 2007. The gut runs a pretty disciplined campaign which you couldn't say for McCain and certainly not Romney.
You do know that the 47% figure tossed around is largely old folks, young students and others who work but dont make enough to pay federal income taxes. They still pay other taxes like payroll, local, etc.
Besides, what's funny and sad at the same time is a good chunk of that 47% comes from...