On an anxious day of waiting, President Bush scrutinized final battle plans Wednesday and told Congress why he was poised to launch the largest pre-emptive attack in U.S. history.

The president stayed out of the public eye even as his 8 p.m EST deadline for Saddam Hussein to leave his country or face war passed.

"The disarmament of the Iraqi regime will begin at a time of the president's choosing," said his press secretary, Ari Fleischer, moments after the deadline passed. "The American people are ready for the disarmament of Saddam Hussein. They understand what's at stake. The military is ready, the nation is ready and the cause is just."

After meeting yet again with Pentagon officials, including Defense Secretary Donald H. Rumsfeld, Bush had just finished dinner Wednesday night and was in the living room of the White House residence with first lady Laura Bush when his chief of staff, Andrew Card, called. Card informed the president hat intelligence officials had no information that Saddam had left Iraq.

Earlier, Fleischer spoke of somber realities of war.

"Americans ought to be prepared for loss of life," he said.

Extra security enveloped the executive mansion while aides inside whispered rumors of Iraqi defections and surrenders.

One official rushed past the Oval Office at lunchtime, glanced at his watch and grimaced. Eight more hours, he said.

The president began his day with the usual briefing from FBI Director Robert Mueller and CIA Director George Tenet. He also met throughout the day with his war council, including Rumsfeld, Vice President Dick Cheney, Secretary of State Colin Powell and National Security Adviser Condoleezza Rice.

They reviewed the final details for war in Iraq, aides said, poring over weather forecasts and troop positions.

Bush also discussed battle plans by telephone with Prime Minister Tony Blair, who has sent 40,000 British troops to the Persian Gulf.

An Oval Office address that would announce the beginning of hostilities was nearly complete. White House speechwriters had been working on it for days.

Bush himself sent Congress formal notice that he had determined "further diplomatic and other peaceful means alone" would not be enough to contain the "threat posed by Iraq." Bush has contended that Saddam possesses chemical and biological weapons that he could use on his enemies or slip to terrorists.

Bush closed the window to diplomacy Monday when he addressed the nation, but the congressional notification was required under the terms of a resolution passed last year to authorize military action.

The resolution also required Bush to verify that ousting Saddam would not hurt the global war on terrorism. Bush complied with a seven-page report asserting that Iraq supports terrorist networks, including Usama bin Laden's Al Qaeda organization.

Offering fresh justification for war, the report said one of the spoils of victory may be information about terror cells in the United States.

"United States government personnel operating in Iraq may discover information through Iraqi government documents and interviews with detained Iraqi officials that would identify individuals currently in the United States and abroad who are linked to terrorist organizations," the report said.

White House officials said the assertion was mostly speculative.

The United States has initiated attacks in such places as Grenada and Panama, but war in Iraq would set a new standard for pre-emptive military action.

Fleischer offered no promises of a swift or easy conflict.

"On the brink of war with Iraq, Americans should be prepared for what we hope will be as precise, short a conflict as possible, but there are many unknowns and it could be a matter of some duration," the spokesman said.

The president also met with New York Mayor Michael Bloomberg, who emerged from the White House to say the long national debate about whether to go to war is over.

"The president has listened and he has made his decision, and I know all New Yorkers are behind him and the troops overseas," the mayor said. "He's not going to be cowed or dissuaded. He's going to go out there and do what we all pray is right."

Bloomberg made a pitch for more money to help his city prevent a terrorist attack and respond to any that occurs.

The president, who warned Monday that terrorists might retaliate for a U.S. attack on Iraq, promised that a war spending bill soon going to Congress would include money to help communities combat and respond to terrorism.

New York and Washington were attacked by terrorists on Sept. 11, 2001. Though Iraq was not implicated, the strikes set Bush on a course to combat terrorism across the globe -- a mission that eventually led him to the brink of war with Saddam.