Though the two polls differed on the current approval ratings for the president, they both revealed a steady decline in his popular standing.
The Zogby America poll said only 45% of Americans gave Bush positive marks for job performance, down from 52% in August and the lowest since January 2001.
The other poll, conducted by Time-CNN said the president's approval stood at 52%, having slid from 63% in May.
"The economy is clearly the chief concern," pollster John Zogby said, noting that recent surveys found more people feared losing their jobs in the coming year.
Iraq, where US soldiers continue to face daily attacks, has also hurt Bush's standing, Zogby said.
"There is growing concern and impatience about whether the war was worth it," the pollster said.
The Time-CNN poll, however, said 72% of people surveyed thought the US had done a "good job" in Iraq since major fighting ended and 63% felt going to war with Iraq was the right decision.
The Zogby poll covering 1,013 people was conducted between 3-5 September. The Time-CNN poll covered 1,003 people and was conducted on 3-4 September.