This isn't really a good question. Whose fault is what? The state of the American economy? The state of the government? The deficit?
There's lots of blame to go around, but this is largely irrelevant. What does it matter, really? No one can deny the Obama administration failed to accomplish a lot of what was promised. No one can deny the GOP engaged in reckless obstructionism with the singular goal of unseating Obama.
At this point, trying to blame a single person or even a single side is counterproductive. You've got the government you've got. The GOP controls the house. The democrats control the senate. The president is a Democrat. Perhaps it's time to move forward instead of staring backwards.