This is going to be a Blame Bush II campaign. He can't run on his record, so he has to do something. It won't work for him this time. He is already going down in history as the whining and blaming President who couldn't even pass a budget.
While I'm sure "Blame Bush" will be part of it, I can think of at least three other strategies Obama will be using:
1. Class warfare. In every speech, Obama (The president who was supposed to be the Great Unifier who would gloriously bring Americans of all beliefs together in harmony) will moan about the evil rich people supposedly destroying our country, portray Romney and the GOP as a whole as being among those evil rich people, and encourage hatred of such people. Anyone opposed to Obama's Socialistic policies will be portrayed as an evil, greedy, selfish miser who doesn't want to do anything to help the poor. He did it in his first campaign, he'll do it in this one.
2. Race- baiting. Obama (Again, the supposed Great Unifier) deliberately inflamed racial tensions with his remarks about the Trayvon Martin shooting, I have little to no doubt he will continue inflaming those tensions as part of his campaign strategy. Romney and anyone else who criticizes Obama will be openly accused of racism for no good reason, and conservatives as a whole will be portrayed as evil, lame, racist white men.
3. Religious hatemongering. Obama will undoubtedly bring Romney's religious beliefs up as a way to discredit him. I'm reminded of a political cartoon I saw when Romney was still a contender in 2008. It was at a Romney press conference, a spokesman says, "Does anyone have any questions for Governor Romney?", and the reporters all raised their hands. In the next panel, the spokesman says, "Any questions which DON'T involve the fact that he's a Mormon?", not not a single hand remained up.