Bush and Cheney only agreed to Thursday's unprecedented interview under pressure and on the grounds they would appear together and behind closed doors.

At the administration's request, the session will not be recorded and an official transcript will not be made. The White House said Bush was already providing unprecedented access to the panel and that the decision was consistent with previous private interviews.

"This is a private interview and it's being treated that way," said commission spokesman Al Felzenberg.

Both sides said they will have note-takers present.

In preparation for Thursday's session, White House spokesman Scott McClellan said Bush was reviewing documents and meeting with his top advisers.

He said Bush does not plan to make an opening statement and is likely to personally field most of the questions -- rather than Cheney. They will not be under oath.

While details of the commission's line of inquiry remain secret, it is clear from previous public hearings that the panel of five Republicans and five Democrats will press for answers to a now-famous Washington question: "What did the president know and when did he know it?"

Past testimony has established that elements of the U.S. intelligence apparatus were aware of threats to American targets from the militant al Qaeda network, led by Osama bin Laden.

McClellan said the president's demands for secrecy -- which were not applied to national security adviser Condoleezza Rice or other top Bush officials during their public testimony -- would not undermine the process.

"The president will tell it exactly how it happened," he said.

Stenographers/Recordings Barred

But Democrats say the White House insistence the two appear together may be an attempt to eliminate the possibility of contradictory testimony over whether the administration did all it could to head off the Sept. 11 attacks.

Bush is "at risk of being branded as unwilling to stand alone and take the heat," warned University of Texas political scientist Bruce Buchanan, a longtime Bush watcher, could side step future calls for making the full testimony public.

Former President Bill Clinton's appearance before a grand jury in the Monica Lewinsky scandal was recorded on video tape and later released.

Bush already has met with Rice, Chief of Staff Andrew Card and White House counsel Alberto Gonzales to prepare for the session. McClellan said Gonzales' office has provided Bush with "documents from that time period to refresh his memory."

McClellan defended the White House approach, saying that having Bush and Cheney appear together would help commissioners piece together the events of that day and complete their recommendations. He said Cheney would take questions if asked directly, but that Bush was expected to take the lead.

Bush's advisers are worried the commission's findings will be critical of Bush, who is running for re-election in November on his record of fighting terrorism.

Bush, who initially opposed creation of the independent commission, had earlier insisted he meet with just the panel's chairman and vice chairman, and for only one hour.

Under pressure from the commission, however, Bush agreed to meet all 10 members -- five Republicans and five Democrats -- and to answer questions for as long as necessary.

"This is not an adversarial process," McClellan insisted. "He (Bush) looks forward to answering whatever questions they may have."

A main area of questioning for Bush is expected to be claims by former U.S. counterterrorism chief Richard Clarke that he ignored an urgent al Qaeda threat before the attacks.

The closed-door meeting is expected to begin at 9:30 a.m. (1330 GMT).

McClellan said this level of secrecy was justified to protect the highly classified information that may be discussed.

McClellan said he expected Gonzales and at least one other member of the White House Counsel's staff to attend.

The 9/11 commissioners will be allowed to bring along one staffer, most likely Philip Zelikow, their executive director.

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