President Barack Obama's tumbling poll numbers have dipped below those of his predecessor George W. Bush at the same point in his White House tenure, according to a national poll released Tuesday.

Obama's approval rating is 55 percent six months into his presidency, a USA Today/Gallup poll found. But 56 percent of those polled approved of the job done by George W. Bush after six months, the daily reported.

Obama's handling of the economy appears to be key in his fading popularity, as Americans become more pessimistic about how long it will take the economic downturn to end.