The latest Gallup Poll found that Bush's popularity had been below 40 percent for six consecutive quarters, the Dallas Morning News reports. Nixon ended his five-quarter streak by resigning in 1974.

Truman's approval ratings were below 40 percent for 10 months, the longest ever in the history of the Gallup Poll. Bush, with six quarters remaining in his second term, could surpass Truman.

Bush would like to see himself as a Truman, a president far more popular in retrospect with historians and even the public than he was while he was in office, but political observers aren't so sure.

"If Iraq goes down, Bush joins the Nixon pantheon," said Bruce Buchanan, a University of Texas expert on presidential politics. "If it doesn't, he may be able to live up to his hero Truman."