A U.S. president's legacy is perhaps best left to historians with the benefit of time and hindsight. But in the present, President George W. Bush's approval ratings have been on a steady slide since his high-flying popularity right after his response to the terrorist attacks of Sept. 11, 2001.

Survey: Worst Presidents Ever?

The Gallup organization reported that Bush had a record-high 90 percent approval in those late days of 2001. The mark broke Harry S. Truman's recorded 87 percent approval in 1945 just after V-E Day.

But according to a Sept. 26-27 USA Today/Gallup poll, 27 percent of Americans approve of the job Bush is doing. It's the lowest rating of his presidency, and it threatens again to eclipse Truman, whose February 1952 approval rating was 22 percent.

Bush has already sunk lower than President Jimmy Carter, whose lowest approval rating was 28 percent in July 1979. And Bush has pulled almost even with President Richard M. Nixon, who in May 1975 had a 25 percent approval rating.

Gallup has measured U.S. president approval since the Eisenhower administration.