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National Security Adviser Condoleezza Rice (search) will testify publicly and under oath before the commission investigating the Sept. 11 attacks in order to bring truth to the American people, President Bush said Tuesday.

Bush said he approved having Rice testify because "I consider it necessary to gaining a complete picture of the months and years that preceded the murder of our fellow citizens on Sept. 11, 2001."

The National Commission on Terrorist Attacks on the United States (search) wants to question Rice about what counterterrorism meetings and strategy discussions she was privy to in the days leading up to and following the devastating Al Qaeda attacks in New York and Washington in 2001.

The decision to allow Rice to testify was a change of heart for the Bush White House, which until Tuesday had objected to Rice testifying in open session before the commission. Bush officials were concerned that requiring an adviser to the president, as opposed to a Cabinet official, to testify before the panel in public and under oath would violate the separation of powers between the executive and legislative branches of government.

But all 10 members of the bipartisan commission clamored for Rice to testify, especially after the highly critical testimony last week of Richard A. Clarke, the former top counterterrorism adviser to both Bush and former President Clinton. Clarke, in his testimony and in his new book, has said the current White House didn't treat the threat from Al Qaeda (search) with enough urgency.

Several commission members pointedly mentioned Rice's absence at last week's hearings — particularly when they questioned Deputy Secretary of State Richard Armitage.

Bush told reporters at the White House Tuesday that the "exceptional nature of this inquiry" helped convince him that he needed to have Rice testify to the commission — and by extension talk to the American people under oath. Rice has already spoken with the panel for four hours, but this was done in a closed session and she was not sworn in.

More than 800 members of the Bush administration — including more than 20 White House officials — have met with the commission so far, Bush said.

Also set to speak to the commission, although in private, are Bush, Clinton, Vice President Cheney and former Vice President Al Gore.

"I know my responsibility as well, to act against the continuing threat and to protect the American people," Bush said.

The first sign that the White House was changing its position on the Rice testimony came Tuesday morning when White House Counsel Alberto Gonzales (search) sent a letter to the commission laying out what it was prepared to do and what it needed in return.

"The president recognizes the truly unique and extraordinary circumstances underlying the commission's responsibility to prepare a detailed report on the facts and circumstances of the horrific attacks on September 11, 2001," Gonzales wrote, while asking that the commission make clear Rice's testimony would be treated as a unique event.

Click to read the letter from White House Counsel Alberto Gonzales.

The commission issued a statement praising the decision and agreeing with the White House's interpretation of how Rice's testimony should be viewed.

"We agree with the observation by the president's counsel that Dr. Rice's appearance before the Commission is in response to the special circumstances presented by the events of September 11 and the Commission's unique mandate and should not be viewed as a precedent for future requests for public testimony by White House officials," the statement said.

Click to read the statement from the Sept. 11 commission.

The commission's Republican chairman, former New Jersey Gov. Thomas Kean (search), welcomed the decision and said the White House shouldn't be concerned that the testimony would violate the principles of executive privilege or separation of powers.

"We recognize the fact that this is an extraordinary event. There are all sorts of reasons why this is different. This does not set a precedent," he told reporters. He said there was still no time set — either for Rice's public testimony or for Bush and Cheney's private appearance.

Commissioner Slade Gorton (search), a former Republican senator from Washington, said the Sept. 11 panel accepted the proposal in a meeting Tuesday morning, including the stipulation that it not call other White House officials because "we hadn't planned to."

"I think the White House would have been better off if it had made the agreements sooner, but I'm delighted," said Gorton. "I have felt all along that her public testimony would be good for the country."

Commissioner Bob Kerrey (search), a former Democratic senator from Nebraska, said the president and vice president will not be under oath in their meeting with the commission. Kerry said Rice's testimony will be critical in determining what the Bush administration could have done to prevent the attacks and that the White House "made the right decision."

Initially Rice rejected testifying in public, arguing that she was prevented by executive privilege (search) from revealing confidential conversations. She later clarified that she wanted to testify, but couldn't because of the president's concerns that her testimony would violate the separation of powers.

Democrats, meanwhile, said the White House decision was a good start, but didn't address all their concerns.

"The Bush administration has finally come to its senses on what should have been a simple issue by reversing its previous refusal to allow the national security adviser to testify in public under oath," said House Democratic Leader Nancy Pelosi (search). "The Bush administration needs to understand that the independent 9/11 commission seeks truth, not blame."

Fox News' Wendell Goler, Jim Angle, Sharon Kehnemui and Catherine Donaldson-Evans as well as The Associated Press contributed to this report.