TRUMAN WENT LOWER President Bush's 29% approval rating leaves him still more popular than Harry Truman at the low point of his presidency. Truman's rating dipped to 22%. History regards Truman better than Americans did in 1952, says Alonzo Hamby, Ohio University history professor and Truman biographer. Truman's prosecution of the Korean War was unpopular at home. The conflict, which ended in 1953 and cost 36,000 American lives, is looked on more favorably today by historians for helping to establish a stable democratic South Korea, Hamby said. Among Truman's controversies, he fired Gen. Douglas MacArthur, whom many considered a hero. Suspicions of communist infiltration of the U.S. government led Truman to initiate loyalty reviews that led to hundreds of dismissals. He seized the steel industry in 1952 to prevent a strike. And scores of officials resigned in a bribery scandal at the IRS. By William M. Welch

Bush's approval rating has reached a new low: 29%.

In the survey, taken Friday through Sunday, one in five Americans say the increase in U.S. forces in Iraq since January has made the situation there better. Half say it hasn't made a difference.

More than seven in 10 favor removing nearly all U.S. troops from Iraq by April.

Still, 55% say Congress should wait to develop a new policy on Iraq until Gen. David Petraeus, commander of U.S. forces in Iraq, delivers a promised assessment in September; 40% say Congress should act now.

The White House is scrambling to prevent more defections among Republicans in the debate over the defense authorization bill, a platform for amendments on the war. Such senior GOP senators as Richard Lugar of Indiana and Pete Domenici of New Mexico in recent days have called on Bush to change course in Iraq.

"It makes it much harder for him to hold any Republican in the House or Senate," says Dean Lacy of Dartmouth College, who studies public opinion. "They have to run for re-election. They realize now that Bush can't help them at all; he may hurt them."

White House spokesman Tony Fratto declined to discuss the findings. "We really don't pay much attention to polls," he says. "I know they're fun, self-generating news hooks, but we don't make policy decisions based on which way the wind is blowing."

Bush's support is eroding among Republicans: 68% approve of him, down from an average 92% in his first term, 82% in his second. Nearly 4 in 10 Republicans say the immigration debate, which ended in defeat for Bush's overhaul proposal, caused them to lose confidence in him.

The poll of 1,014 adults has an error margin of +/—3 percentage points for the full sample, 5 points for the GOP subsample.

The results reflect broad dissatisfaction with Bush and the country's direction:

•Sixty-two percent say the United States made a mistake in sending troops to Iraq, the first time that number has topped 60%.

•Two-thirds say Bush shouldn't have intervened in the case of former White House aide Lewis "Scooter" Libby, who was sentenced to 2½ years in prison for perjury and obstruction of justice in the investigation of who leaked a CIA operative's identity. Bush voided Libby's prison sentence but let his conviction stand.

•Six in 10 say the economy is worse than it was five years ago, and the same number predict that economic conditions are getting worse.

Bush now has had both the highest approval rating in Gallup's history — 90% in the aftermath of the 9/11 attacks — and one of the lowest. Among modern presidents, only Richard Nixon, Harry Truman and Jimmy Carter ever had a lower rating.

By 62%-36%, those surveyed say an impeachment inquiry against Bush, promoted by some liberal websites including ImpeachBush.com, wouldn't be justified. House Speaker Nancy Pelosi says Congress has no intention of holding such proceedings. Republicans oppose the idea 91%-9%. Democrats support it 54%-44%.