An Iraqi opposition leader here to meet top Bush administration officials said Baghdad's forces would succumb quickly in the event of a U.S. invasion, but a prominent Republican expressed reservations about an unprovoked attack.

Sharif Ali, a lead member of the Iraqi National Congress, said all Iraqis have abandoned their president, Saddam Hussein, and that he and his colleagues in the anti-Saddam coalition would present a united front in their discussions with State and Defense Department officials.

Ali said the London-based INC has militants inside and outside of Iraq who are prepared to cooperate with U.S. forces in the event of an attack. He suggested that victory for American forces over Saddam would come more easily than many -- including some military experts -- suspect.

"The entirety of Iraq is opposed to Saddam Hussein," he said, mentioning specifically the Republican Guard units that are sometimes described as the backbone of his support.

But House Majority Leader Dick Armey, R-Texas, in a speech Thursday in Des Moines, Iowa, cautioned against an unprovoked U.S. attack against Saddam.

"My own view would be to let him bluster, let him rant and rave all he wants," Armey said, indicating a crack in Republican support for President Bush's push to topple Saddam. "As long as he behaves himself within his own borders, we should not be addressing any attack or resources against him."

Speculation has been rampant about a U.S. attack on Iraq, but the White House said Thursday that Bush had made no decisions.

Armey warned that striking Iraq without a clear and easily understood provocation would isolate the United States.

"If we try to act against Saddam Hussein, as obnoxious as he is, without proper provocation, we will not have the support of other nation states who might do so," Armey said.

A new CBS poll says two-thirds of Americans support military action against Iraq, but they want Bush to get prior congressional approval. The same number said they believe the United States needs to wait to build support with its allies before acting against Iraq.

Bush has promised to consult with Congress and allies before taking any action against Saddam.

The rationale for considering military action is the administration's belief that Saddam is developing weapons of mass destruction that could threaten Iraq's neighbors and the United States.

Supporters of an attack say the provocation the United States needs is Saddam's refusal to allow weapons inspectors into his country, one of the terms of ending the Gulf War. Armey disagreed.

"In my estimation it is not enough reason to go in, that he does not allow weapons inspections," he said.

The Gulf War was a different story, Armey said, because Saddam had moved beyond his own borders into Kuwait.

"He is what we in Texas know as a blowhard. He can't help himself," said Armey, who is retiring from Congress this year. "We Americans don't make unprovoked attacks against other nations."

The Iraqi opposition leaders had a midafternoon meeting scheduled with Undersecretary of State Marc Grossman and Undersecretary of Defense Douglas Feith. Leading the Iraqi delegation for Friday's meeting was Ahmed Chalabi, who heads the INC.

The Iraqis will speak via secure video linkup Saturday with Vice President Dick Cheney, who is spending August at his Wyoming home.

Saddam said Thursday his forces would dispose quickly of any invading force. "The forces of evil will carry their coffins on their backs to die in disgraceful failure," the Iraqi leader said.

A U.S. intelligence official said Iraq's strategy is to avoid war with the United States by strengthening ties with its neighbors and appearing open to some level of international weapons inspections.

If war comes, Iraq's best option is to try to force the United States to fight in the cities, the official said.

Saddam knows that the high civilian casualties caused by urban combat would be distasteful to the Americans and their European allies. Urban warfare also limits the utility of precision airstrikes, as U.S. bombers try to avoid collateral damage to civilian buildings.

The precise role of the INC in any U.S. attack on Iraq is the subject of debate. Some officials believe the INC could replicate the role that the northern alliance rebels played in Afghanistan last fall in helping U.S. forces defeat the Taliban.

Others believe INC is ineffective and cannot be counted on to serve as U.S. partners in the event of an American attack.