A congressional committee examining pre-Iraq war intelligence holds its first public hearing Thursday on Capitol Hill, as the controversy over information used by the Bush administration to support the case for military action continues. The hearing of the House of Representatives Committee on Intelligence comes as the head of a key Senate panel vowed to press a separate investigation there.

For weeks, separate House and Senate panels have been pouring over intensively examining at least 20 volumes of intelligence sent to Congress by the CIA.

Since much of the intelligence has been highly classified, whatever hearings have occurred have been closed to the public.

That will change when the House Intelligence Committee holds an open hearing expected to focus on whether the Bush administration had sufficient, high quality, intelligence about Iraqi weapons of mass destruction efforts.

Among the witnesses will be former heads of the CIA and others in the intelligence community with knowledge of the intelligence-gathering process.

Both the Republican chairman of the House committee, and its top Democrat, say they are committed to ensuring that a thorough investigation of the pre-war intelligence issue is completed.

Republican Congressman Porter Goss, who chaired the House committee, said the Africa uranium issue will be a key part of the House probe. "The Niger subject is in hand at our committee. As you know, we made a public statement some time ago that we would be doing a thorough WMD review. We, in fact, are doing it. It is ongoing. And I can tell you that even our trip we gathered some information that is relevant to that," he said.

Mr. Goss referred to a recent trip to Iraq by committee members. He said it's not yet clear how credible the information they obtained concerning the Iraq/Africa uranium question is.

Congressional Republicans have accused Democrats, including those running for the White House in 2004, of trying to make political capital out of the controversy.

On Wednesday, the White House renewed charges that Democrats are "revising history" in an attempt to use the WMD issue as a political weapon. White House spokesman Scott McClellan said, "I think it's just still nonsense, and in some cases outrageous, that some partisan Democrats would try to do one of two things, either have it both ways, because there is an overwhelming bipartisan congressional resolution that supported the action we took. And some people now are trying to change what they previously said, and essentially try to have it both ways. Their current rhetoric just doesn't match their past statements."

However, the latest revelation by a White House aide about mishandling of CIA warnings about intelligence on Iraq-Africa uranium connections may have slightly weakened the Republican argument.

Stephen Hadley, a deputy national security advisor, has said CIA warnings about intelligence concerning alleged Iraqi attempts to buy uranium in Africa should have prevented the information from appearing in the president's State of the Union Address.

Senator Pat Roberts, who chairs the Senate Intelligence Committee, has formally asked the White House to allow Mr. Hadley, and possibly others, to testify.

Senator Roberts denies assertions he initially opposed holding public hearings, and now says they will begin in September. He explained on C-SPAN television why the information being examined needed to be handled carefully. He said, "The information we are going through, floor-to-ceiling documents, contains all of the source material that leads up to a conclusion of what has happened on the issue of WMD and why we went to war, the Niger documents, all of the things that you're concerned about. And that information is highly classified, it is classified top secret code word. If we were to have public hearings and reveal that kind of information, it would reveal our methods and sources, it would certainly put U.S. lives (at) risk."

President Bush has said the overall threat from Iraqi President Saddam Hussein, including his weapons development efforts and support for terrorist causes, constituted a "clear and compelling" reason to go to war.

White House spokesman McClellan said Wednesday the president sees no need to address the American people to clear up misunderstandings they may have about the intelligence issue.

Some members of Congress say this would be a positive step the White House could take, but add that it would still not put the controversy to rest.