Secretary of State Colin Powell plans to lay out Thursday the U.S. position on Iraq's weapons declaration and whether the Bush administration intends to claim Iraq is in "material breach" of a U.N. arms resolution that threatened war unless Saddam Hussein disarms.

Saddam missed his "last chance" to come clean with the world, the White House said Wednesday, as President Bush debated whether to formally declare Iraq in violation.

In a series of meetings, the president and his advisers swung back and forth on the question of whether Iraq is in "material breach" of the United Nations, which would provide what Bush considers legal justification for war.

Senior administration officials, speaking on condition of anonymity, said Wednesday afternoon that Bush had decided to strongly condemn Iraq's weapons disclosure as full of omissions and deceptions but would not immediately assert that Saddam is in "material breach."

Later, those same officials and others involved in the talks said the issue was reopened for debate Wednesday night, and Bush seemed to be leaning toward finding Saddam in violation.

The Pentagon, meanwhile, continued preparations for possible war. As many as 50,000 troops may be deployed in early January for duty in the Persian Gulf area, according to officials who spoke Wednesday on condition of anonymity. They said Defense Secretary Donald H. Rumsfeld had not yet signed the deployment order. More than 50,000 U.S. troops are already in the Gulf region.

Whether he finds Saddam in violation now or waits several weeks, officials said, Bush plans this week to launch a deliberative diplomatic process that would push the prospects for military action into late January or February.

The senior administration sources spoke on condition of anonymity after Bush met with his foreign policy team to sketch out strategy in response to Iraq's 12,000-page weapons declaration.

Working through weapons inspections, Bush intends to press the United Nations to demand interviews outside of Iraq with Saddam's scientists — forcing a showdown that Bush believes would bolster his case for war or reveal secrets of Saddam's arsenal, officials said.

"My guess is that the United States will take some time and will talk to some of our friends and allies around the world about the [Iraqi] declaration and share ideas and thoughts about what's in it and what may not be in it," Defense Secretary Donald H. Rumsfeld said in a televised interview.

Powell said the U.S. analysis of the Iraqi declaration "shows problems with the declaration, gaps, omissions, and all of this is troublesome." Rumsfeld said the U.S. analysts reviewing the declaration "are still trying to find things ... that they expected to be there that weren't there."

The White House suggested Bush had problems with the declaration beyond previously disclosed omissions concerning chemical and biological weapons last noted in Iraq four years ago.

Bush, who plans to address the matter Friday, wants to soothe anxious allies and keep his pledge to have "zero tolerance" for the Iraqi president defiance — a balance aides concede won't be easy to strike.

Iraq's declaration, required under a U.N. resolution, asserts that Saddam has no weapons of mass destruction — a claim the United States says it is prepared to rebut.

"We are not encouraged that they have gotten the message or will cooperate," Powell said.

Rumsfeld said Iraq's chemical and biological arsenals are more formidable than during the 1991 Persian Gulf War.

"In weapons of mass destruction, one has to believe they are much stronger," Rumsfeld said. "So, it is a dangerous business, and he [Saddam] is engaged in a dangerous game."

Bush intends to use lapses in the declaration as evidence of Saddam's ill intent, increasing pressure on U.N. weapons inspectors to use all their powers to uncover Iraq's deceits, the officials said. He will allow weapons inspectors to continue their work, aided by an increase in U.S. intelligence about Saddam's weapons program, sources said.

Powell and John Negroponte, U.S. ambassador to the United Nations, will outline Bush's position Thursday, with the president planning to address the issue Friday — perhaps in a brief encounter with reporters.

Also Thursday, the United Nations' nuclear chief will tell the Security Council that further inspections are needed to verify Hussein's claims, U.N. officials said. Mohamed ElBaradei, joined by chief U.N. weapons inspector Hans Blix, will make a case for more inspections, said an official with the U.N. nuclear regulatory agency.

Administration officials said a key date in the standoff will be Jan 27., when Blix is scheduled to make his first complete report to the Security Council on Iraq's compliance. That falls well within the optimal window for a winter attack on Iraq, officials noted, and gives the U.S. time to build its case against Saddam.

Under the terms of Resolution 1441, passed Nov. 8, false statements or omissions in the declaration — coupled with a failure to comply with inspections — would be a "material breach" of Iraq's obligations to disarm.

Saddam has thus far complied with inspections, but hard-liners in the administration want Bush to liberally interpret the resolution's language. They argue that Saddam is taking advantage of a two-step test for "material breach" and should be found in violation if he violates either the inspections or the declaration provisions.

Bush believes Saddam will resist demands under the U.N. resolution to bring scientists out of Iraq for interviews, violating his agreement to cooperate with inspectors and giving the United States a stronger case for "material breach," officials said.

Presenting the administration's opening argument, White House spokesman Ari Fleischer told reporters that Saddam has missed the final opportunity to come clean about his weapons of mass destruction.

"This was Saddam Hussein's last chance," he said, while promising a "deliberative, thoughtful" U.S. response.

The "last chance" comment evoked Bush's warning in November that should Saddam deny possessing weapons of mass destruction "he will have entered his final stage with a lie." Officials said that final stage begins Friday, when Bush issues his formal assessment, and could end in war several weeks from now.

The Associated Press contributed to this report.