After Secretary of State Colin Powell conferred by telephone with Foreign Minister Bill Graham, the State Department spokesman Richard Boucher said the proposal "only procrastinates on a decision we all should be prepared to take."
Boucher recalled other governments tried earlier to set a deadline for Iraq. But he said, in the meantime "we have heard from inspectors again, again and again" that Iraq had not agreed to fully disarm.
Earlier, President Bush called Saddam Hussein "a master of disguise and delay" Wednesday and mocked the Iraqi leader for disclosing some weapons that he'd previously denied were in his arsenal.
On a day in which the White House threatened Saddam with trial as a war criminal in the event of war, Bush said, "The danger with Iraq is that he can strike in the neighborhood and the danger with Iraq is that he has got the willingness and capacity to train al-Qaida type organizations and provide them with equipment to hurt Americans."
Saddam "will be disarmed one way or the other," the president declared as his administration prepared for another faceoff at the United Nations on a resolution designed to bring about the disarmament of Iraq.
In remarks before the Latino Coalition, however, Bush stopped short of repeating previous claims of an already existing link between Iraq and al-Qaida terrorists. But he did say, "The world has waited a long time for Mr. Saddam Hussein to disarm."
From the speech, Bush stepped into a meeting with President Geidar Aliev of Azerbaijan, a country 250 miles northeast of Iraq, which has backed the U.S. call for Iraq's disarmament.
On Tuesday, Bush said that if the Iraqi president and his generals "take innocent life, if they destroy infrastructure, they will be held accountable as war criminals."
In other developments:
Bush was to give a speech on Iraq later Wednesday at the American Enterprise Institute, a conservative Washington think tank from which he drew many of his aides.
He was expected to argue that Saddam is a menace to the Iraqi people and that getting rid of him would make the Middle East - including the volatile Israeli-Palestinian conflict - more stable.
Bush also was to stress the prospects for democracy in a post-Saddam Iraq and the United States' intention to address humanitarian needs caused by possible war, said his spokesman, Ari Fleischer.
Offering Congress and the American public a peek into war and postwar preparations, the Army's top general said Tuesday that a military occupying force could total several hundred thousand soldiers.
Iraq is "a piece of geography that's fairly significant," Gen. Eric K. Shinseki said at a hearing of the Senate Armed Services Committee. Any postwar occupying force, he said, would have to be big enough to maintain safety in a country with "ethnic tensions that could lead to other problems."
Shinseki said he couldn't give specific numbers of the size of an occupation force but would rely on the recommendations of commanders in the region.
"How about a range?" asked Sen. Carl Levin of Michigan, the senior Democrat on the committee.
"I would say that what's been mobilized to this point, something on the order of several hundred thousand soldiers," the general said. "Assistance from friends and allies would be helpful."
Afterward, Levin called Shinseki's estimate "very sobering."
On Wednesday, the White House sought to minimize the impact of Shinseki's testimony, with Fleischer declining to repeat his estimate. "It's impossible to guess the exact numbers of people that would be involved in any longer-term effort," he said.
In a speech prepared for Wednesday delivery to the Council on Foreign Relations, Sen. Joe Lieberman, D-Conn., was calling on the Bush administration to work with the United Nations to name an international administrator to oversee reconstruction of Iraq.
A U.S. civilian administrator "would put America in the position of an occupying power, not a liberator," said Lieberman, who is running for the Democratic nomination for president in 2004. "And it may well widen the gulf between the United States and the Arab world."
In northern Iraq, which was pried from Saddam's control to protect Kurdish civilians after the 1991 Persian Gulf war, White House and State Department officials were holding a meeting with political opponents of Saddam's government. The aim was to help plan the kind of government that would take over in Baghdad after an ouster of Saddam.