President Bush's national security adviser is scheduled to give three hours of testimony before the bipartisan the Sept. 11 commission. Her testimony will be televised nationally by CBS News, and webcast live on CBSNews.com.
White House aides have said that Rice will mount a strong defense of the Bush administration's approach to terror in the months before the Sept. 11 attacks.
She is also expected to rebut the claims of former counterterrorism chief Richard Clarke, who has asserted that Mr. Bush and others at the White House did not devote enough attention to the threat of a terrorist attack.
Rice is to begin her testimony with a 20-minute statement outlining the administration's position. The New York Times reported that Rice will speak directly to family members of victims of the attack.
Clarke created the most dramatic moment of previous 9/11 hearings when he turned to family members seated in the audience and apologized for the government's failure to prevent the attacks. The Times said Rice has no plans to make a similar apology.
Mr. Bush said Monday that Rice "knows exactly what took place and will lay out the facts" when she testifies before the Sept. 11 commission.
"She's a very smart, capable person who knows exactly what took place and will lay out the facts," Mr. Bush told reporters while on an economic and fund-raising trip to North Carolina.
Her testimony was assured only after the White House changed course last week under pressure and decided to allow her to appear publicly and under oath. She has testified in a private session in February.
Rice is not the only person who will feel pressure before the cameras.
If 9/11 panel members appear politically motivated in their questioning of the national security adviser, it could raise questions about their credibility — and the findings in their final report this summer.
Thomas H. Kean, the panel's Republican chairman, says he and Democratic vice chairman Lee Hamilton are mindful of the political overtones in a presidential election year.
They issued an edict to fellow commissioners after last week's politically charged testimony from former government counterterror chief Richard Clarke. The message: Leave politics out of it.
"In a very difficult atmosphere, in a town that is the most polarized I've ever seen, the commission is trying to do a job for the American people that is to the best of our ability nonpolitical," Kean said in an interview. "That is enormously hard to do, but I think we can get it done and people should leave us alone."
Nolan McCarty, a Princeton University professor of politics and public affairs, said Rice's testimony will offer a stern test for the panel.
"Partisanship is almost inevitable," he said. "There's going to be pressure from all quarters to reach specific conclusions either in exonerating the current administration or blasting the previous administration or the reverse. This may be the low point."
Kean, a former New Jersey governor, expressed frustration with people in Washington who he said are intent on politicizing the commission's work. While panel members are political appointees who have diverse points of view and different constituencies, they are fair-minded and get along well, he said.
The 10-member panel is made up of five Republicans and five Democrats.