The latest Harris Poll puts George W. Bush's popularity at just 29%. The poll data came from the time period before the most recent news of widespread NSA surveilance of US citizens.
This puts Bush's popularity lower than any two-term president at this point of his administration. Only two presidents have ever scored lower approval ratings: Richard Nixon and Jimmy Carter. Bush Jr.'s approval rating now ties the lowest approval rating of his father, George Herbert Walker Bush.
No sitting president whose popularity has fallen below 30% has ever had his popularity rise back above 35%.