The birther issue
death panels (there was a grain of truth, but the claims were wildly overblown)
The evil liberal billionares
calling him a socialist/communist/fascist
the claims that the healthcare bill would bankrupt us
the pinning the economy on him (when it clearly failed before he was even elected)
blaming him for the stimulus not being effective (when it clearly was)
The idea that the stimulus cost less than the iraq war (which requires some very fuzzy math)
The claim that Obama's mere presence introduces uncertainty and this being the primary reason the economy has not recovered.
probably some other stuff that I will think of later.
Basically, the conservatives have been on operation smear job since day 1 and truth was the casualty. They do not care about the good of the nation, only winning the next election. *
* there are always reasonable people on all points of the spectrum.
Now obviously the administration has made some missteps, such as the nature of the stimulus, being too close to wall street when america was clearly going populist (this is where he lost the public), failing to articulate a vision (letting the republicans assign him one), not being aggressive enough for main street, and leaving too much up to congress. Also, the health care bill had some seriously bad timing and should have been tackled during a boom.