I think that no one can accuse Obama. His reign was just 14 months. American economy was in trouble for several reasons like
1. War on Afganistan
2. War on Iraq
3. Sub Prime Mortgage Crisis
4. Works are being outsourced to other countries.
I dont think these had occured during the reign of Obama. After becoming the President of America, he leived taxes on companies which are outsourcing thier works to other countries, this will reduce the unemployment which is at 10% right now.