Vice President Cheney today accused political opponents of engaging in "corrupt and shameless" revisionism by charging that the Bush administration misled the nation into the Iraq war, and he warned that any sudden withdrawal of U.S. forces from Iraq "would be a victory for the terrorists."

In a speech at the American Enterprise Institute, a conservative Washington think tank, Cheney struck back at Democratic lawmakers who have sharpened their criticism lately of the way the administration used prewar intelligence to justify invading Iraq in March 2003. Cheney repeated assertions -- disputed by some senators -- that members of Congress had access to the same intelligence that was provided to President Bush about the threat of Iraqi weapons of mass destruction under the rule of Saddam Hussein. No stockpiles of such weapons have been found.

Referring to similar comments he made in a speech last week, Cheney sought to draw a distinction between legitimate debate and what he has called "dishonest" and "reprehensible" charges.

His comments come amid recriminations over a call by Rep. John P. Murtha, a Pennsylvania Democrat known as a hawk on military issues, for an immediate withdrawal of U.S. forces from Iraq. Murtha, a 37-year veteran of the Marine Corps who was wounded in Vietnam, said in an emotional speech Thursday that the U.S. military has done all it can in Iraq and that it was now "time for a change in direction."

In part, Cheney's remarks echoed comments by Bush Sunday in Beijing as the president sought to tone down the vitriol that administration officials, Republican lawmakers and GOP officials directed at Murtha following his call for a pullout. Republicans described Murtha's proposal as cowardly, accused him of wanting to "surrender to terrorists," called him a hypocrite and charged he was aligning himself with extreme liberals. Murtha hit back at criticism from Cheney last week by noting that the vice president never served in the military and had sought five deferments to avoid having to go to Vietnam.

Murtha today defended his call for a troop withdrawal from Iraq, telling reporters in his hometown of Johnstown, Pa., "The public turned against this war before I said it." He said Americans want "a solution to this thing, and that's what I hope this administration is going to find out," the Associated Press reported.

Sen. John F. Kerry (D-Mass.) charged today that Cheney is "trying to avoid the real debate" and persists in misleading the nation.

"He continued to insult those of us who think there's a better way in Iraq," Kerry said in prepared remarks in Boston in response to Cheney's speech. "No matter what the vice president says, asking tough questions isn't pessimism; it's patriotism. I believe that during wartime, we should ask the hardest questions of all. It's the only way to do what's right for our troops instead of repeating the same mistakes over and over again."

Kerry added: "The vice president continued to mislead America today by saying Congress saw and heard the same intelligence the White House did. We did not."

In Washington, Senate Minority Leader Harry M. Reid (D-Nev.) said Cheney's speech today "was yet another missed opportunity by the vice president to come clean with the American people and lay out a strategy for success in Iraq." In a statement, Reid said Cheney and the Bush administration "continue to ignore the facts and lash out at those who raise legitimate questions about how the administration misused intelligence in its rush to war."

Cheney said in his speech today that he does not believe it is "wrong to criticize the war on terror or any aspect thereof" and that he enjoys "energetic debate on issues facing our country." He called Murtha "a good man, a Marine, a patriot" and said that while he disagreed with him, the congressman was "taking a clear stand in an entirely legitimate discussion."

However, Cheney said: "What is not legitimate and what I will again say is dishonest and reprehensible is the suggestion by some U.S. senators that the president of the United States or any member of his administration purposely misled the American people on prewar intelligence. Some of the most irresponsible comments have come from politicians who actually voted in favor of authorizing the use of force against Saddam Hussein. These are elected officials who had access to the intelligence materials. They are known to have a high opinion of their own analytical capabilities. And they were free to reach their own judgments based upon the evidence."

Although the United States has not found any stockpiles of banned weapons in Iraq, Cheney said, "I repeat that we never had the burden of proof; Saddam Hussein did."

Cheney added: "The flaws in the intelligence are plain enough in hindsight. But any suggestion that prewar information was distorted, hyped or fabricated by the leader of the nation is utterly false."

He called this "revisionism of the most corrupt and shameless variety" and said it "has no place anywhere in American politics, much less in the United States Senate."

"One might also argue that untruthful charges against the commander in chief have an insidious effect on the war effort itself," Cheney said. "I'm unwilling to say that only because I know the character of the United States armed forces."

He assured service members and their families that "their cause is right and just and necessary, and we will stand behind them with pride and without wavering until the day of victory."

A "retreat" by U.S. forces in Iraq would "convince the terrorists that free nations will change our policies, forsake our friends, abandon our interests whenever we are confronted with murder and blackmail," Cheney said. "A precipitous withdrawal from Iraq would be a victory for the terrorists, an invitation to further violence against free nations and a terrible blow to the future security of the United States of America."

Despite this "self-defeating pessimism," Iraq is making "real progress," and the United States will remain steadfast, Cheney said.

"The terrorists . . . have contempt for our values, they doubt our strength and they believe that America will lose its nerve and let down our guard," he said. "But this nation's made a decision: We will not retreat in the face of brutality, and we will never live at the mercy of tyrants or terrorists."