Mr. Bush was preparing to name the panel Friday, but White House spokesman Scott McClellan said final details were still being worked out. Meanwhile, the president was meeting with the new head of the Iraqi arms hunt, Charles Duelfer.
The White House has yet to reveal the names of any of the nine commission members, but an administration official, speaking on condition of anonymity, said Sen. John McCain, R-Ariz., would be one.
But the president is making sure the commission will not supply ammunition for his Democratic challengers. The nine-member panel won't report until after the election.
In addition, the president will ask it for a "broad" look at America's ability to detect clandestine arms programs in totalitarian states.
Administration officials say that in addition to assessing how well U.S. intelligence did in determining the existence of Iraqi weapons of mass destruction, the commission also will look at the bigger picture of fighting terrorism and monitoring U.S. adversaries, such as those in Iran and North Korea.
Democrats have charged the panel is a ploy to avoid accountability on Iraq. And they doubt it will be unbiased, since Mr. Bush is choosing all the members.
Sensing a campaign issue in this election year, Democrats have been clamoring to find out whether the White House pressured analysts or manipulated intelligence, but it's not clear whether the commission will address those areas.
David Kay, the former CIA adviser for the Iraqi weapons search, said Thursday that the commission should look into whether political leaders manipulated intelligence data.
"I think that is an important question that needs to be understood," he said at the Carnegie Endowment for International Peace.
Kay repeated statements made last week that he doesn't believe analysts were pressured to make the case for war.
It was Kay's criticism of prewar intelligence since resigning two weeks ago that built momentum for an independent commission. Kay said intelligence agencies wrongly concluded that Iraq had stockpiles of chemical and biological weapons because they had too little human intelligence and overanalyzed the data in hand.
On Thursday, CIA Director George Tenet says intelligence analysts gave the White House an objective view of the threat posed by Iraq, but didn't address the question of how the Bush administration presented that information to the American public.
The question of whether intelligence was manipulated has deeply divided the Senate Intelligence Committee, which is completing its own inquiry.
Committee members reviewed a classified draft report Thursday that is believed to be critical of U.S. intelligence agencies' work. But Democrats have said the inquiry was too narrow because it didn't examine how the administration used the intelligence. Both parties have accused each other of trying to use the investigation for political purposes.
In a forceful defense of prewar intelligence in a speech at Georgetown University on Thursday, Tenet said the analyses were reasonable given the information available to the United States and other nations.
"Based on an assessment of the data we collected over the past 10 years, it would have been difficult for analysts to come to any different conclusions than the ones reached in October of 2002," when a comprehensive intelligence estimate was prepared.
Agreeing with Kay that political pressure was not a factor, Tenet said, "No one told us what to say or how to say it." He also didn't rule out that weapons still could be found.
But Tenet added that analysts "never said there was an imminent threat," Tenet said. "Rather, they painted an objective assessment for our policy makers of a brutal dictator who was continuing his efforts to deceive and build programs that might constantly surprise us and threaten our interests."
Before the war, Mr. Bush and his senior advisers made clear they viewed the threat from Saddam as urgent. On Sept. 13, 2002, Mr. Bush said of Saddam, "He's a threat we must deal with as quickly as possible." The next month, he said "the danger is already significant and it only grows worse with time."
White House aides have pointed out that Mr. Bush, while he cited the urgency of stopping Saddam, never called the threat "imminent." But if the threat wasn't imminent, why the move to war while U.N. inspections were still under way?
Speaking in Charleston, S.C., Mr. Bush defended the decision to go to war.
"Knowing what I knew then and knowing what I know today, America did the right thing in Iraq," the president said.
But Democratic presidential candidates said Tenet's speech showed that Mr. Bush misled Americans.
Democratic front-runner Sen. John Kerry of Massachusetts said Mr. Bush and other officials "were playing politics with our national security." Retired Gen. Wesley Clark said, "The question now is: What did (Bush) know at the time?"