WASHINGTON (CNN) -- President Bush on Thursday said he told visiting king of Jordan that he is "sorry for the humiliation suffered" by Iraqi prisoners at the hands of U.S. troops in Iraq.
Bush said he told King Abdullah II that the photos made him and others "sick to our stomachs." And he said he made it clear that "wrongdoers will be brought to justice."
Bush made his comments at a joint Rose Garden news conference with the king.
Bush rejected calls for Defense Secretary Donald Rumsfeld to resign for his handling of the Iraqi prisoner abuse controversy.
"He is an important part of my Cabinet and he will stay in my Cabinet," Bush said.
Earlier in the day, Sen. Tom Harkin, D-Iowa, demanded Rumsfeld leave office.
"For the good of our country, the safety of our troops, and our image around the globe, Secretary Rumsfeld should resign," Harkin said in a statement. "If he does not resign forthwith, the president should fire him."
"He has to go. Nothing, I think, less will suffice," Harkin told CNN. "It's not enough just for Secretary Rumsfeld to say that some people in the lower ranks are responsible for this -- this goes all the way up."
Rumsfeld is scheduled to testify Friday morning about the U.S. military abuse of Iraqi prisoners in both open and closed hearings of the Senate Armed Services Committee.
An internal report by the U.S. Defense Department determined that Iraqi prisoners were being abused by members of the U.S. military.
Investigators, led by Maj. Gen. Antonio Taguba, interviewed dozens of witnesses and looked at "numerous photos and videos portraying in graphic detail actual detainee abuse" that were taken by personnel at Abu Ghraib prison on the outskirts of Baghdad.
The report said the abuse included threatening detainees with a pistol and with military dogs, sodomizing a prisoner with a chemical light and perhaps a broomstick, forcing naked prisoners into compromising positions and accusing them of being homosexuals.
Six soldiers have been criminally charged in the case and six others have been reprimanded, with two of those relieved of duty, Rumsfeld has said.
After last week's CBS broadcast showing images of Iraqis being humiliated and abused, both Democrats and Republicans on Capitol Hill have expressed outrage that they were not informed of the problem earlier.
House Minority Leader Rep. Nancy Pelosi, D-California, said Rumsfeld's statement that the Army made the abuse investigations public in January was an insufficient explanation for not telling Congress about details of the abuse problem.
"Mr. Rumsfeld has been engaged in a coverup from the start on this issue and continues to be so," Pelosi said Thursday.
Like Harkin, Rep. Charles Rangel, D-New York, also called for Rumsfeld to resign or be removed from office, saying the Pentagon chief concealed the matter from Bush and Congress.
The Economist magazine Thursday called for Rumsfeld to resign as did an editorial in the St. Louis Post-Dispatch. New York Times columnist Thomas L. Friedman called on Bush to fire Rumsfeld "today, not tomorrow or next month."
Rumsfeld canceled a planned speech Thursday to the World Affairs Council in Philadelphia, Pennsylvania, to spend the day preparing for his testimony, Pentagon officials said.
In a private meeting between Rumsfeld and President Bush on Wednesday, Bush told Rumsfeld he was "not happy" that he learned about the photos by watching television, a senior administration official told CNN.
"He was not happy, and he let Secretary Rumsfeld know about it," the official said.
Bush also was concerned that he was not kept up to speed on the scope of the problem -- and how the Pentagon was handling it, the official said.
Rumsfeld also made clear that he, too, felt "he didn't know some things he should have," according to the senior official, along with another official. (Full story)
Meanwhile, the Red Cross said Thursday it had "repeatedly requested U.S. authorities to take corrective action."
Antonella Notari, chief spokeswoman for the International Committee of the Red Cross, said "some measures have already been taken," without revealing the ICRC's recommendations.
"I do think that our recommendations were taken seriously and I do think that now, yet even more, there are other measures that are being planned," she said. "And we do, of course, intend to continue our visits."