The president is centering his re-election campaign on his leadership of the war against terrorism, and that's why the stakes were so high for him and Vice President Dick Cheney in their three-hour-plus session with the commission.
The panel of five Republicans and five Democrats has the potential to deliver a heavy blow to the president later this year in the thick of the presidential race. It issues its final report on July 26 — the same day the Democratic National Convention opens in Boston.
Bush supporters worry that the panel's findings will hand Democrats a golden opportunity to step up their criticism of the Republican president's national security stewardship.
"Any report before the election has some risk," said Republican consultant Scott Reed. But Reed also said the commission "seems to be playing it straight in a bipartisan manner. And they're a pox on everyone's house."
Many people close to the investigation expect the report to fault both the current administration and the preceding Democratic administration of President Clinton, in particular the FBI and the CIA, for failing to do more to confront the pre-Sept. 11 threat of the al Qaeda terrorist network.
But there's a big difference. Mr. Bush is on the November ballot; Clinton isn't.
Mr. Bush has made his performance as a wartime president — and the assertion that the world is safer with Saddam Hussein out of power — a guiding theme of his re-election campaign.
If the commission's report undercuts this central premise, it could be politically damaging to a president who is running hard to keep his job.
CBS News Chief White House Correspondent John Roberts reports, evidence emerged Thursday that might undermine the president's claim.
In a speech to a terrorism conference six months before the Sept. 11 attacks, Paul Bremer, now Mr. Bush's point man in Iraq warned: "The new administration seems to be paying no attention to the problem of terrorism. What they will do is stagger along until there's a major incident and then suddenly say, 'Oh my God, shouldn't we be organized to deal with this?' They've been given a window of opportunity with very little terrorism now, and they're not taking advantage of it."
The commission told CBS News that it might be interested to hear more about Bremer's speech.
During Thursday's meeting, Mr. Bush and Cheney fielded a broad array of questions about the lack of a U.S. military response after the 2000 bombing of the USS Cole that killed 17 American sailors and an Aug. 6, 2001, presidential brief Mr. Bush received a month before the attacks warning that Osama bin Laden was preparing to strike.
In a brief meeting with reporters in the Rose Garden after his meeting, Mr. Bush was asked if he could say with any confidence that there are no al Qaeda terrorists in the United States today. "No, I can't say that," he responded.
He said that was one question the commission didn't ask him.
"I answered every question they asked," Mr. Bush said after the meeting. "I think it helped them understand how I think and how I run the White House and how we deal with threats." He said there was a lot of discussion about how to protect the nation better.
"We are still vulnerable to attack," Mr. Bush told reporters. "And the reason why is al Qaeda still exists, al Qaeda's dangerous, al Qaeda hates us. And we have to be correct 100 percent of the time in defending America and they've got to be right once."
It was Mr. Bush who responded to most of the questions, officials said. Cheney spoke only when Mr. Bush turned to him about details he didn't know, according to one participant.
"It was an extraordinarily good meeting. The president was forthright," said former New Jersey Gov. Thomas Kean, the commission's Republican chairman.
Democratic commissioner Bob Kerrey described some of the answers as "surprising" and "new" but declined to give details. "I think the less I say that could be construed as critical, the better chance we have of reaching consensus when we write our final report."
Kerrey, along with Lee Hamilton, the commission's vice chairman, left the Oval Office meeting early because of what they said were prior commitments.
The White House initially had opposed creation of the commission and later raised objections to extending its term, balked at Mr. Bush being questioned by all of the commission members and tried to prevent Condoleezza Rice, the president's national security adviser, from testifying in public under oath.
Unlike the commission's private meeting with former President Bill Clinton and former Vice President Al Gore, the meeting was not recorded or transcribed. While details will be included in the panel's final report, they may deleted from the version for public release if the White House deems the information classified.
"We would have hoped there would have been some sort of record of the meeting for the annals of history," said Kristen Breitweiser, whose husband Ronald died in the World Trade Center. "It is enormously important for the American public to have an open, transparent dialogue and debate on our nation's ability to defend ourselves."