The search for weapons of mass destruction in Iraq continues and so too does the hunt for a government scapegoat if weapons of mass destruction are never found.

The Senate Select Committee on Intelligence  (search) is about to release a report that is highly critical of the CIA's work.

And the intelligence agency has already gone on the defensive, saying it's too soon to conclude the intelligence was unfounded while the search for weapons of mass destruction in Iraq continues.

"It is hard to understand how the committee could come to any conclusions at this point, particularly while the efforts of (weapons search leader) Dr. David Kay (search) in Iraq are at an early stage," said CIA spokesman Bill Harlow.

Harlow said "the committee has yet to take the opportunity to hear a comprehensive explanation of how and why we reached our conclusions," nor has it accepted an offer made Wednesday by CIA Director George Tenet (search) to hear from him and senior intelligence officials.

The Washington Post reported Friday that the bipartisan Senate committee, which is reviewing pre-war intelligence, will blame the CIA for using single-source information and circumstantial evidence about Iraq's pursuit of weapons of mass destruction. The panel apparently has interviewed more than 100 people and pored over volumes of classified material.

Democrats have increasingly blamed President Bush for hyping the threat in the run-up to the Iraq war. Bush just returned to Washington from a six-nation tour of Asia.

On Thursday, the president defended the war on terror during a fund-raising speech in Hawaii, arguing that wars against the Taliban (search) in Afghanistan and Saddam Hussein (search) in Iraq freed millions from despotism and reduced the threat of terrorism.

"In Afghanistan and Iraq, we gave ultimatums to terror regimes," Bush said. "Those regimes chose defiance and those regimes are no more. Fifty million people in those two countries once lived under tyranny, and now they live in freedom."

Investigations by House and Senate Intelligence committees appear to place most of the blame on the CIA, not the White House.

In comments to the Post, Kansas Republican Sen. Pat Roberts (search), chairman of the Intelligence Committee, said the U.S. intelligence community let the White House down.

"I worry about the credibility of the intelligence community," said Roberts, who added that he is concerned about demoralizing the intelligence agencies when intensive counterterrorism operations are going on overseas. Still, he insisted, "If there's stuff on the fan, we have to get the fan cleaned."

Fellow Republicans appeared eager to echo that sentiment.

"I trust his [Roberts'] judgment, and his indication that the president was not well served by the intelligence community has to be taken seriously," Sen. Thad Cochran, R-Miss., told Fox News.

He added: "I think it's very important that we get the facts right when we make these judgments about going to war, especially when we're going to go on a preemptive war when we attack first."

The CIA has long defended its pre-war Iraq intelligence, saying it matched what other western intelligence agencies feared Iraq was up to. The CIA also has long said intelligence gathering in one of the most secretive and oppressive regimes on the planet was never going to yield absolute proof.

"I think what we've learned here that we didn't have the human sources on the ground that we'd like to have," said Fox News military analyst, Ret. Lt. Col. Bill Cowan.

The United States relied heavily on satellite imagery, information gleaned from predator drones and other sorts of electronic and signal intelligence to get information about Saddam's weapons and other potential threats.

"I would say we didn't do a very good job -- weapons of mass destruction was our one big issue going into Iraq we had to date we haven't found any," he said. "We have to question" whether the intelligence was good.

Defending the CIA's National Intelligence Estimate (search), which has been a focus of criticism, Harlow noted that it was produced "in record time, at the insistence of members of the United States Senate."

"The committee has yet to take the opportunity to hear a comprehensive explanation of how and why we reached our conclusions," Harlow said, adding that Tenet has requested a chance for the CIA's senior leadership to appear before the committee "to help them understand this important and complex subject."

Fox News' Major Garrett and The Associated Press contributed to this report.