Bush gives Saddam 48 hours to leave Iraq or face war.

Byline: Ron Hutcheson and Martin Merzer

WASHINGTON _ President Bush delivered a final ultimatum Monday night to Iraqi leader Saddam Hussein: exile or war _ decide by Wednesday night.

"Saddam Hussein and his sons must leave Iraq within 48 hours," Bush said during a prime-time address to the nation. "Their refusal to do so will result in military conflict, commenced at a time of our choosing."

Iraqi officials said Saddam would not leave. "He will stay in place like a solid rock," Iraqi Information Minister Mohammed Saeed al-Sahhaf told the al Jazeera television service.

As Bush spoke, federal authorities elevated the nation's domestic terror threat level to high (orange) from elevated (yellow) and announced an enhanced security program called Operation Liberty Shield.

Without providing many details, authorities said they were tightening security at borders, airports, seaports and elsewhere. Homeland Security Secretary Tom Ridge urged governors to deploy National Guard units to high-risk locations.

The stark developments came just hours after the administration withdrew its pending U.N. resolution, suffering a stunning diplomatic defeat, and the United Nations suspended weapons inspections in Iraq.

"The United Nations Security Council has not lived up to its responsibilities, so we will rise to ours," the president said.

Bush based his case for war primarily upon the need to prevent Iraq from …