President George W. Bush (news - web sites) "absolutely" still has confidence in Rumsfeld, White House spokesman Scott McClellan told reporters. The spokesman deflected questions about whether the defense secretary should resign with a curt "No."
Bush has sought to repair the damage caused by the scandal by going before Arab television news cameras a short time later to denounce the abuses at the Abu Ghraib prison as as "abhorrent."
Rumsfeld also went on television talk shows to promise investigations and defend the Defense Department's performance amid an international uproar that shows no sign of subsiding a week after CBS television aired shocking photographs of naked Iraqi prisoners in humiliating poses.
Though the allegations of abuse were first made in January, the secretary confronted the issue publicly for the first time only on Tuesday.
Members of Congress from both parties were incensed that they had been kept in the dark for months about the gravity of the situation.
"Who is in charge? Who has made these decisions? Why have there not been any sound decisions made recently," Senator Joe Biden, ranking member of the Senate Foreign Relations Committee, asked Wednesday on NBC television.
Biden, who charged that Bush had been "ill served" by the Pentagon (news - web sites), was asked whether he was suggesting Rumsfeld should resign.
"I sure am," he said. "If it goes all the way to Rumsfeld, then he should resign."
Senator John McCain, an independent-minded Republican who sits on the Senate Armed Services Committee (news - web sites), said it was not yet time to seek Rumsfeld's resignation.
"But clearly there has to be a full, complete, independent investigation," he told ABC television.
McCain said no member of the armed services committee had been alerted to the scandals before the story broke on CBS.
"Everything that I can tell is we were not communicated with at least to the degree of the severity of this situation," he said.
Rumsfeld has clashed repeatedly with Congress over the past three years for keeping a close hold on information about everything from plans to transform the military to post-war planning to the cost of operations in Iraq (news - web sites).
But the prison scandal has been particularly acute because it comes at a time of growing alarm in Congress over the state of the US-led occupation -- with a mounting US death toll, deepening Iraqi hostility, and no clear political solution in sight.
Top Pentagon leaders made matters worse by giving the impression they had wilfully ignored signs that the military-run detention system in Iraq had run amok.
General Richard Myers, the chairman of the Joint Chief of Staff, told a television interviewer on Sunday that he had not read a damning report by an army major general that pointed to egregious violations at Abu Ghraib.
As of Monday, a spokesman acknowledged that Rumsfeld also had not read the report by Major Antonio Tabuga.
"The report as I understand it is a stack -- a report coupled with a whole series of annexes," Rumsfeld said in an interview Wednesday with NBC television.
"And so, when I am asked a question as to whether I have read the entire report, I answer honestly that I have not. It is a mountain of paper and investigative material," he said.
But Rumsfeld said investigations were launched immediately after the allegations of abuse were made, and an announcement was made in Baghdad that a criminal investigation had been opened.
"The system worked, and it was announced publicly. There was no secret about it," he said.