"You are doing a superb job. You are a strong secretary of defence," Bush said during a trip to the Pentagon, situated just outside Washington, on Tuesday.

Bush spoke before television cameras flanked by Rumsfeld, Vice President Richard Cheney, Secretary of State Colin Powell, Iraq's newly-approved US ambassador John Negroponte and Joint Chiefs of Staff Chairman Richard Myers in a show of administration unity.

The president spoke after viewing classified pictures, similar to the graphic photographs that have hit the front pages of US newspapers, showing abuse of Iraqi prisoners at Abu Ghraib prison in Iraq by US soldiers.

"It does not represent our United States military and it does not represent the United States of America," Bush said, adding that there will be a "full accounting" for the events inside Abu Ghraib.

However, in throwing his full weight behind his defence chief, the Republican president has decided to turn a deaf ear to growing calls for Rumsfeld to resign from opposition Democrats and the US media.

"It was not surprising that partisan Democrats went for the secretary of defence's throat. The shocker was how few friends of the Bush administration jumped to his aid," wrote conservative columnist Robert Novak in a Monday editorial in the Chicago Sun-Times.

The ongoing fallout from the "sadistic" abuse as it has been termed by an investigating US Army general, appear to be reflected in new opinion polls.

A survey published Monday by CNN/USA Today, taken between May 7 and 9 as the scandal first surfaced, shows president Bush's overall popularity rating has fallen to 46 percent, the lowest reading since he entered office in January 2001.

The number of those who disapproved of Bush climbed to 51 percent, passing the 50-percent-mark for the first time.

However, Bush appears to be holding a wafer-thin margin over Democratic Senator John Kerry who is campaigning against him ahead of the November 2 US presidential election, with 48 percent of support compared with 47 percent for Kerry.

The poll's margin of error was three percent.

Rumsfeld's approval rating meanwhile is in freefall, according to the poll, falling to 46 percent from 58 percent last October, but only 29 percent of respondents thought he should resign.

Support for the Iraq war has dropped to 44 percent from 50 percent at the start of May, marking the first time since the fall of Baghdad in April 2003 that a minority have shown support for the conflict.

For Bush, who is campaigning across the country as a commander-in-chief, the latest poll readings are likely to be troubling.

The incumbent president appears to be betting that American and world emotion and anger over the Abu Ghraib photos will recede, even if new photos and possibly video footage comes into the public domain.

But Bush has weathered choppy waters already.

The resignation in December 2003 of his treasury secretary Paul O'Neill, followed by O'Neill's claims that the administration wanted to oust Saddam Hussein from the moment it entered office, did not seriously harm Bush's standing.

Likewise, strong criticism from the administration's former antiterrorist chief, Richard Clarke, who accused the White House of negligence in preempting terror attacks has also diminished.

"The problem for Bush is that sacking his war minister in time of war is not the same as dismissing a feckless secretary of the treasury," added Novak, in underlining the tricky position facing the president.