In one of the darkest weeks of his administration, President Bush saw America's reputation sullied, the U.S. effort in Iraq (search) damaged and his own campaign for re-election clouded. And more bad news may be on the way.

While the world already has been horrified by pictures of American soldiers abusing Iraqi prisoners, the Pentagon warns there are many more photos and videos that have not been disclosed.

They show "acts that can only be described as blatantly sadistic, cruel and inhuman," embattled Defense Secretary Donald Rumsfeld (search) told Congress.

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From the White House to Capitol Hill, policy-makers are worried that the United States faces lasting damage abroad — particularly in the Middle East — from the pictures of naked Arab men being tortured and humiliated by American soldiers, the same forces sent to Iraq to liberate the country from Saddam Hussein's torture and repression.

Analysts describe the pictures as great recruiting tools for Al Qaeda (search) and other extremist groups and said they undermine America's claims to a moral high ground. Rumsfeld said the impact was "radioactive."

Bush, in his weekly radio address Saturday, said, "They are a stain on our country's honor and reputation." He said the abuses were the work of a few and do not reflect the overall character of the 200,000 members of the U.S. military who have served in Iraq in the past year.

Six months from the November elections, Iraq weighs heavily on the president.

April was the deadliest month yet for American soldiers in Iraq and May is off to a bloody start.

On the diplomatic front, the administration does not know who will take power in Iraq from the United States in a June 30 handover.

Costs are soaring. The administration has sent Congress an unexpected $25 billion request for Iraq and Afghanistan.

Day after day, the extraordinary apologies from the president and his top deputies dominated the news.

Pollsters and presidential experts are scratching their heads over how the prisoner scandal will affect Bush's re-election hopes.

"There's such a big question mark there, it's unlike anything we've seen before," said Andrew Kohut, director of the Pew Research Center.

"The public is very critical of [Bush's] management of Iraq. They don't think he has a clear plan for bringing it to a successful conclusion, but a thin majority of the public has been hanging in with that it was the right decision to go to war," Kohut said. "This could be the event which makes people say 'Oh, we did make a mistake.'"

Political scientist James Thurber of American University likened the Iraq images to the infamous Vietnam pictures of a naked young girl fleeing a napalm attack and a Viet Cong prisoner being executed on a Saigon street.

Referring to the new pictures, Thurber said, "That's what we're going to remember about Iraq. It's just not going to go away. That may have a lasting and negative effect on his campaign. It certainly does right now and I think you'll see it in the polls immediately."

Support for Bush's handling of foreign policy and terrorism, usually his strongest issue, was at 50 percent in an Associated Press-Ipsos poll released Friday. That compares with 55 percent a month ago.

Kurt Campbell, a former Pentagon official during the Clinton administration, said it was too early to tell whether Rumsfeld would be able to keep his job.

"The real issue is there's more stuff that's going to come out that is troubling, beyond humiliation and torture. Deaths I think," said Campbell, director of international security at the Center for Strategic and International Studies.

"And there's going to be quite a long record of warnings that were either ignore or dismissed. And that I think is going to be problematic," Campbell said.

Lawmakers worried the pictures would harm U.S. credibility for years, perhaps decades. While the United States champions freedom and democracy in Iraq, the pictures show vivid scenes of cruelty and insensitivity.

Splashed across front pages across the Middle East and around the world, the pictures may undermine "the substantial gains toward the goal of peace and freedom in various operation areas of the world, most particularly Iraq," said Sen. John Warner, R-Va., chairman of the Senate Armed Services Committee.

Michigan Sen. Carl Levin, the committee's top Democrat, said the abuses "dishonored our military and our nation and they made the prospects for success in Iraq even more difficult than they already are."

Added Rep. Tom Cole, R-Okla.: "This was a political and public relations Pearl Harbor."

Bush pledged in his radio address that the United States would not be thrown into retreat.

"This has been a difficult few weeks," Bush said. "Yet our forces will stay on the offensive, finding and confronting the killers and terrorists who are trying to undermine the progress of democracy in Iraq."