US:President George Bush's top aides struggled yesterday to persuade a sceptical public and a hostile Congress that the president's plan to send more troops to Iraq represented the last, best chance for victory.
As some Republicans joined Democrats to condemn the plan, secretary of state Condoleezza Rice and defence secretary Robert Gates defended the change of strategy.
"This is a time for a national imperative not to fail in Iraq," Ms Rice told the Senate foreign relations committee.
With opinion polls showing more than 70 per cent of the US public opposed to the troop increase, Republican senator Chuck Hagel described the president's plan as "the most dangerous foreign policy blunder in this country since Vietnam".
Mr Hagel is among up to a dozen Republicans expected to support a senate resolution condemning the new strategy, which would send 21,500 additional troops to Iraq over the next five months.
In a sharp exchange with Mr Hagel, Ms Rice claimed that the troop build-up did not represent an escalation of the US's military engagement in Iraq.
"Putting in 22,000 more troops is not an escalation? Would you call it a decrease?" Mr Hagel said.
"I would call it, senator, an augmentation that allows the Iraqis to deal with this very serious problem that they have in Baghdad," Ms Rice replied.
The committee chairman, Democrat Joseph Biden, pressed Ms Rice to say whether she was confident that Iraqi prime minister Nouri al-Maliki would be capable of providing enough Iraqi troops to help stabilise the country.
"I think he knows that his government is in a sense on borrowed time," she said.
Ohio Republican George Voinovich told Ms Rice that she would have to do a better job making the case for the war in Iraq, adding that the president could no longer count on his support.
"I've gone along with the president on this and I've bought into his dream and at this stage of the game I just don't think it's going to happen," Mr Voinovich said.
Earlier Mr Gates said the president's new strategy was built on the lessons and experience of the past four years.
"At this pivotal moment, the credibility of the United States is on the line in Iraq. Governments in the region, both friends and adversaries, are watching what we do and will draw their own conclusions about our resolve and the steadfastness of our commitments. Whatever one's views on how we got to this point in Iraq, there is widespread agreement that failure there would be a calamity that would haunt our nation in the future, and in the region," he said.
Mr Gates said he has asked the president to add 92,000 soldiers and marines to the US military over the next five years, with an emphasis on increasing combat capability.
As the president yesterday began promoting his strategy across the US with an appearance before a military audience at Fort Benning, Georgia, Democrats considered their legislative options for influencing the campaign in Iraq.
Both houses of Congress will vote on non-binding resolutions condemning the plan but the Republican leadership is seeking to taunt Democrats into an early vote to cut off funding for the war. Senate majority leader Harry Reid and House speaker Nancy Pelosi have ruled out taking any action that could adversely affect US forces in the field but Democratic senator Russ Feingold, who opposed the war from the beginning, said yesterday it was time for Congress to consider cutting off funds.