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For the second day in a row, President Bush (search) lashed out at those criticizing him for not finding chemical and biological weapons in Iraq, calling the naysayers "revisionist historians."

Speaking at an employment training center in suburban Washington, D.C., Bush reprogrammed a 2000 campaign slogan: "A charge we've been given and a charge we'll keep," applying it to what he says is the common threat posed by global terrorism and rogue regimes like Saddam's.

"We made it clear to the dictator of Iraq that he must disarm," Bush told staff and visitors at Northern Virginia Community College (search). "And we asked other nations to join us in seeing to it that he would disarm and he chose not to do so, so we disarmed him. And I know there's a lot of revisionist history now going on, but one thing is certain: He is no longer a threat to the free world and the people of Iraq are free."

Aides say the president still believes the threat from the weapons was urgent enough to justify the war. Critics contend the intelligence community exaggerated its information on Iraq.

"If there was shading by the intelligence community to try to support what it perceived to be the policy of the administration or for whatever reason, it would endanger our security," Sen. Carl Levin, D-Mich., ranking member of the Senate Armed Services Committee, said Monday.

On Monday, Bush visited a frozen pasta business in New Jersey to tout the tax cut passed last month. While there, he took the opportunity to express his impatience with the nagging criticism.

"This nation acted to a threat from the dictator of Iraq. Now, there are some who would like to rewrite history — 'revisionist historians' is what I like to call them," Bush said.

According to Bush, the revisionists are those who have called into question whether the war was justified inasmuch as the United States has not yet found the weapons of mass destruction the president and others cited as one of the key reasons for going to war.

A senior adviser said Bush decided it was "time to go on the offensive" to head off the "growing 'where are the weapons?' movement."

"Congress has been a full partner [on the issue] going back a decade and has received information both in open and closed session," the aide said. "Go back to the speeches of 1998. Look at ... how many lawmakers said Saddam Hussein has weapons of mass destruction. Do they think since the [United Nations] inspectors left, Saddam got rid of that?"

While Bush did not discuss the details of the hunt for weapons of mass destruction, the administration is stepping up efforts to find them, sending former U.N. weapons inspector David Kay (search), now a special adviser to the CIA, to Iraq.

Kay will devise a strategy to search for such weapons and will work hand-in-hand with the 1,300-member military force known as the Iraq Survey Group (search), which is in charge of finding the weapons.

Members of the Senate Intelligence Committee (search) announced this weekend that it will investigate charges of exaggerated intelligence. The House Intelligence panel has already announced its own inquiry. Hearings, probably behind closed doors, will include questioning of intelligence analysts about their work.

Though the president's aide said Bush does not resent the idea of a congressional investigation, Bush asserted that the United States went to war to respond to a very real threat.

"Saddam Hussein was a threat to America and the free world in '91, in '98, in 2003. He continually ignored the demands of the free world, so the United States and friends and allies acted," Bush said on Monday.

Centrist Democrats of the Democratic Leadership Council (search), who quibble with the president on many fronts, this time agree with Bush, saying the hunt for weapons of mass destruction is not cause for argument.

"If the Bush administration was wrong about Saddam's WMD program, so too was just about everybody else, including U.N. inspectors, the French, the Germans, the Russians and the Chinese, all of whom accepted prior evidence of such a program is beyond doubt," the DLC said in a statement.

Evidence or no evidence, many familiar with the intelligence say they don't believe Saddam voluntarily gave up his weapons after inspectors left in 1998.

"Some are suggesting, certainly, that he destroyed the weapons after 1998 or maybe even sooner," Rep. Jane Harman, D-Calif., ranking member of the House intelligence Committee, told Fox News. "It's just counterintuitive that he would have done that. His would have been the greatest intelligence hoax of all time, fooling every intelligence agency, three presidents, five secretaries of defense and the entire world into thinking he still had the weapons."

Fox News' Jim Angle contributed to this report.