Rice will testify under oath for about 2½ hours on Thursday, with much of the questioning expected to focus on what outgoing Clinton officials told her about the al Qaeda threat and her response afterward.
"She's obviously a very important witness who will be able to share the facts that pertain to the counterterrorism policy in the Bush administration, particularly in its earliest months," said commission spokesman Al Felzenberg. "The commission looks forward to hearing from her."
Rice had resisted testifying publicly in favor of meeting privately with the commission, citing legal concerns. But after mounting pressure, the White House this week agreed to let her appear before the panel after getting commission and congressional assurances that the move would not be seen as legal precedent that could force other presidential advisers before congressional panels.
"We really want to find out about the transition, what they learned, and what changes in policy the Bush administration decided and what focus there was on terrorism," Thomas Kean, the commission chairman, said in an interview.
But Bruce Lindsey, former President Clinton's legal representative for records and a longtime confidant, told The Associated Press that the commission's attempt to get a full picture of Clinton's terrorism policies has been hampered because the Bush administration won't forward all of Mr. Clinton's records to the panel.
Lindsey said the White House has turned over only 25 percent of the 11,000 records requested by the commission.
The White House says it has fully met the panel's information requests.
"Whether documents from the Clinton administration or the Bush administration, we have worked to ensure the commission has all the information it needs to get its job done," Taylor Gross, a White House spokesman, said Thursday.
Rice's testimony could have enormous implications for Mr. Bush's re-election campaign, which rests significantly on his national security credentials. Mr. Bush's former counterterrorism chief, Richard Clarke, testified last week that the administration prior to Sept. 11 did not consider al Qaeda an urgent threat despite his repeated warnings.
Citing legal concerns, the White House had insisted that Rice would only meet privately with the commission, but it relented to mounting political pressure after assurances that the appearance of a senior presidential adviser would not set a precedent applicable to other congressionally appointed panels.
Also Thursday, the White House released portions of a top-secret document, finalized Sept. 4, 2001, that directed the Pentagon to draw up plans for attacking al Qaeda and Afghanistan's ruling Taliban.
The National Security Presidential Directive called on Defense Secretary Donald H. Rumsfeld to plan for military options "against Taliban targets in Afghanistan" and recommended plans "against al Qaeda and associated terrorist facilities in Afghanistan, including leadership, command-control-communications, training and logistics facilities."
The State Department's counterterrorism coordinator testified on Capitol Hill that Osama bin Laden's al Qaeda organization "has been put under catastrophic stress." Cofer Black told a House International Relations subcommittee that 70 percent of al Qaeda's leadership was dead, under arrest or in detention.
For those still at large, "there's a massive global hunt for them under way. It is relentless, 24 hours a day," Black said.
Reps. Henry Waxman, D-Calif., and Carolyn Maloney, D-N.Y., each sent letters to White House counsel Alberto Gonzales asking him to explain why calls were placed to two Republicans on the Sept. 11 commission during Clarke's testimony.
The commissioners — Fred Fielding, a former White House counsel under President Reagan, and James Thompson, a former Illinois governor — questioned whether Clarke had political motives and pointed to earlier instances in which he praised the Bush administration's policies.
White House spokesman Scott McClellan dismissed the notion that Gonzales provided the Republican commissioners with information about Clarke. "Judge Gonzales and the counsel's office is in contact with the commission all the time to make sure they have the information they need to do their job," he said.
Fielding did not return messages left Thursday; an assistant to Thompson said he was unavailable until Monday.
Also Thursday, attention turned to public statements the president and top aides made in the months before the terrorist attacks, particularly a speech Rice was due to give the day of the attacks.
The Washington Post reports Rice was due to make remarks that day that discussed national security threats, but never mentioned al Qaeda or bin Laden. Instead, the remarks focused on the need for missile defense.
And a CBS News review of speeches and public remarks by Mr. Bush suggests he did not mention al Qaeda once before Sept. 11. In one letter to Congress in July 2001, the president referred to al Qaeda and bin Laden in explaining his decision to extend sanctions against the Taliban.
But not all administration officials were as quiet — in public — about bin Laden as others. Addressing Congress in February 2001, CIA director George Tenet said "bin Laden and his global network of lieutenants and associates remain the most immediate and serious threat."
Public statements offer a narrow picture of what the Bush administration was thinking about before Sept. 11. Administration officials contend the policy against al Qaeda was devised in secret.
"The president's commitment to fighting terrorism isn't measured by the number of speeches, but by the concrete actions taken to fight the threat," James R. Wilkinson, deputy national security adviser for communications, told The Post.
But since many of those secret meetings are the subject of the dispute between the White House and former top counterterrorism official Clarke, the public record might get renewed scrutiny.
that the Bush administration did not take his warnings about al Qaeda seriously. Rice and other aides to the president and assailed his credibility.