Actually, the poll isn't especially shocking. As The Hill points out, "52 percent of Americans said President Barack Obama doesn't deserve reelection in 2012" -- a number that is almost identical to the proportion who disapprove of the job he's doing (50%).
For context, a Fox News poll in August 2001 asked the following question about George W. Bush:
Considering how President (George W.) Bush has performed so far, do you think he deserves to be reelected or would the country probably be better off with someone else as president?
The results? 36% said Bush deserved to be reelected, 42% said the country would be better off with someone else, and 22% said it depends or weren't sure. These numbers are actually worse than Obama's relative to the 55% approval/32% disapproval numbers the Fox poll showed for Bush.