(CNN) -- A former White House colleague of Scott McClellan's challenged his assertion in his book that President Bush did not review all the facts before going to war in Iraq, saying, "I don't think he was in a position to know this."
Scott McClellan's book is sparking strong reactions from his former White House colleagues.
"Scott McClellan was not the press secretary. He was the deputy press secretary who dealt with domestic issues," said Dan Bartlett, a former White House counselor. "So, he would not ... have [had] access to the types of meetings and deliberations that the president participated in."
McClellan's new memoir, "What Happened: Inside the Bush White House and Washington's Culture of Deception," is scheduled for publication Monday.
As White House spokesman, McClellan defended Bush's policies during much of the war in Iraq, the aftermath of Hurricane Katrina and the scandal that followed the leak of a CIA agent's identity.
But he now says the administration became mired in propaganda and political spin, and played loose with the truth at times.
In a brief phone conversation with CNN Tuesday evening, McClellan made clear that he stands behind the accuracy of his book. McClellan said that he cannot give on-the-record quotes because of an agreement with his publisher.
But Bartlett said McClellan was not part of and did not witness the deliberations that occurred before the president made the commitment to lead an invasion of Iraq. Watch Bartlett say the White House didn't lie about Iraq »
"That is why it is also a little bit, I think, misguided for him to make these kind of broad accusations and draw these big conclusions about the president," Bartlett said.
Bartlett also said he was troubled by McClellan's assertion that the White House manipulated the public about the existence of weapons of mass destruction in Iraq.
"The fact of the matter was, the weapons of mass destruction weren't there. The intelligence was wrong, but that doesn't make people out to be liars or manipulators or propagandists. It makes them wrong," Bartlett said.
Bartlett said it's "troubling" that McClellan now "gives credibility to every left-wing attack" on anecdotes that are "either thinly sourced or not witnessed by him" in the White House. Bartlett said his assertion that the media were not tough enough on White House before the invasion was "total crap."
But a Clinton White House insider said McClellan's account has credibility because his long proximity to Bush gave him a window on how the war was prosecuted, and he may now be having pangs of conscience.
"I think he has come to the conclusion -- as two-thirds of the American people have -- that it was a bad mistake of judgment on behalf of the president," said John Podesta, a former chief of staff for President Clinton.
Bartlett, like other former White House colleagues, said he was "bewildered and puzzled" by the book because it did not match the Scott McClellan they had worked with. Watch how McClellan's book is shaking up Washington »
"It's almost like we're witnessing an out-of-body experience," Bartlett said.
"We're hearing from a completely different person we didn't have any insight into," Bartlett said, adding that intimates of the president feel that McClellan has violated his trust.
"Part of the role of being a trusted adviser is to honor that trust," Bartlett said.
Many of McClellan's former colleagues echoed current White House spokeswoman Dana Perino, who said, "this is not the Scott we knew."
"There is something about this book that just doesn't make any sense," Ari Fleischer, who proceeded McClellan as press secretary, said in a statement. "For 2½ years, Scott and I worked shoulder to shoulder at the White House. Scott was my always-reliable, solid deputy.
"Not once did Scott approach me -- privately or publicly -- to discuss any misgivings he had about the war in Iraq or the manner in which the White House made the case for war," Fleischer said, adding that he was "heartbroken that Scott feels this way about his time at the White House."
"If Scott had such deep misgivings, he should not have accepted the press secretary position as a matter of principle," Fleischer said.
Fox News contributor and former White House adviser Karl Rove said on that network Tuesday that the excerpts from the book he's read sound more like they were written by a "left-wing blogger" than his former colleague.
McClellan was particularly critical of Rove in his book, saying Rove and fellow White House advisers Elliot Abrams and Lewis "Scooter" Libby had "deceived" him about their involvement in the leaking of the identity of CIA operative Valerie Plame.
For Richard Clarke, the former White House counterterrorism chief who wrote a similar book in 2004, the reaction to McClellan's broadside has a familiar ring. Watch Clarke talk about how the government failed »
"They're saying some of the exact same things about McClellan they said about me," Clarke said.
But he gives McClellan little credit for speaking out now.
"I think the difference with McClellan's book is, he's now telling us something we all know: that the war with Iraq was a disastrous war [and] was sold with deception," he said.
"It's a little different when you say something as I did and a few other people did, four or five years ago, when the war was popular and when we were unpopular for saying what we said."
Clarke left government in 2003. The following year, he accused President Bush of ignoring warnings about the September 11 attacks and of using the attacks to push for war with Iraq.
CNN's Ed Henry contributed to this report.