Updated

President Bush on Thursday night proposed a Cabinet-level Department of Homeland Security to prevent a repeat of the Sept. 11 attacks, calling on Congress to remake the government for "a titanic struggle against terror."

"Tonight, I ask the Congress to join me in creating a single permanent department with an overriding and urgent mission: securing the American homeland and protecting the American people," Bush said in his prime-time address to the nation.

Congress welcomed the proposal, even as it intensified its inquiry into lapses before the Sept. 11 attacks, hearing from an FBI whistle-blower as well as the agency's director.

Bush acknowledged that "suspicions and insights of some of our front-line agents did not get enough attention" and he urged employees of the CIA, FBI and other intelligence agencies to report anything that raises concerns.

"This new department is to be served by the CIA and the FBI," Homeland Security Director Tom Ridge said in an interview with Fox News' Bill O'Reilly. "The president has provided extraordinary leadership."

"We need to know when warnings were missed or signs unheeded — not to point the finger of blame, but to make sure we correct any problems, and prevent them from happening again," Bush said.

Bush spoke to a national TV audience from a lectern placed in the threshold of the White House's Blue Room, with Washington's stormy evening sky visible through the window over his shoulder. On his lapel, was the small American flag pin he has worn since Sept. 11.

The new Department of Homeland Security would inherit 169,000 employees and $37.4 billion in budgets from the agencies it would absorb, including the Secret Service, the Coast Guard, the embattled immigration and customs services.

The White House said it was the biggest government overhaul in a half-century.

"America is leading the civilized world in a titanic struggle against terror," Bush said. "Freedom and fear are at war — and freedom is winning."

Bush said that based on what he knows, "I do not believe anyone could have prevented the horror of Sept. 11. Yet we now know that thousands of trained killers are plotting to attack us and this terrible knowledge requires us to act different."

Congress would have to approve the plan. Bush hopes to have the department in place by Jan. 1.

Bush said the reorganization he proposed was the most extensive since the 1940s, when Harry Truman recognized that America's defenses had to be changed to fight the Cold War.

Similarly, in the aftermath of the Sept. 11 attacks, Bush said: "We are a different nation today: sadder and stronger, less innocent and more courageous, more appreciative of life — and for many who serve our country, more willing to risk life in a great cause."

Reaction was generally positive in Congress, though Democrats said Bush's action was overdue and likely to be overhauled on Capitol Hill.

"I think they saw they were getting behind the wave," said Senate Appropriations Chairman Robert Byrd, D-W.Va.

Sen. Edward Kennedy, D-Mass., said he wasn't sure a reorganization was needed. "The question is whether shifting the deck chairs on the Titanic is the way to go," he said.

White House officials privately acknowledged the proposal could be drastically watered down in turf wars as the affected agencies — and the 88 congressional committees and subcommittees that oversee them — fight to retain power.

The White House unveiled the proposal hours before Bush's address — just as FBI Director Robert Mueller took his seat before the Senate Judiciary Committee to explain why warning signals were missed prior to the September attacks.

"The need for change was apparent even before Sept. 11. It has become more urgent since then," Mueller said in a nationally televised hearing.

Later, FBI whistle-blower Coleen Rowley told the lawmakers mistakes are inevitable in an agency hampered by an "ever-growing bureaucracy."

The White House said its reorganization will not cost more money; it will shuffle current operations within the government without expanding the bureaucracy.

Among the new government functions the president's proposal would create are a threat analysis unit office and an office to coordinate federal programs with state and local officials.

Those additions — as well as the management and administration of the new agency — would be paid for through savings from eliminating redundant functions in other agencies, the report said.

The proposal itself is a marked reversal for Bush. He rejected pleas from Congress last fall to create a Cabinet position and chose instead to install former Pennsylvania Gov. Ridge as an informal adviser. That shielded Ridge from being compelled to testify before Congress.

Ridge was virtually certain to be Bush's choice as the new Cabinet secretary, a position requiring Senate confirmation, aides said. Bush was likely to have a separate White House adviser for homeland security.

The new department would have four divisions:

— Border transportation and security, which would take over the Immigration and Naturalization Service from the Department of Justice, the Customs Service from Treasury and the Coast Guard from the Department of Transportation. The division, with a $23.8 billion budget, would protect the nation's 5,525 miles of border with Canada, 1,989 miles with Mexico and 95,000 miles of shoreline.

— Information analysis and infrastructure protection, which would draw from several agencies including the FBI and CIA to fuse and analyze information about potential threats.

— Emergency preparedness and response, which would include FEMA, now an independent agency.

— Chemical, biological, radiological and nuclear countermeasures, which would take over the Lawrence Livermore National Lab in California. The Departments of Health and Human Services and Agriculture would lose divisions to this office, which would prepare the country for a full range of terrorist threats.

The Secret Service, which specializes in threat assessments and security at high-profile events, would remain intact after moving from Treasury to the new department. It is one of several agencies that would continue their varied non-homeland defense chores at the new department.

The FBI and CIA would remain independent agencies.

But one question remained muddy: just what authority any new secretary of homeland security would have over the FBI and CIA. A senior administration official briefing reporters at the White House said the secretary could not order — only strongly suggest — that the FBI investigate a lead.

Officials said the department probably would have its own federal building, though many of the existing agencies will keep their own. Its budget would be about one-tenth of the Pentagon's, but nearly as much as the $50 billion set aside next year for the Education Department.

Fox News' Wendell Goler, Bill O'Reilly and The Associated Press contributed to this report.