"I haven't made a decision yet," McClellan said. "I have a lot of respect and admiration for Sen. McCain. He is certainly someone who has governed from the center, and that's where I come from; I am pretty much a centrist who believes in working together to solve problems and get things done and putting the country ahead of partisan politics. I also am intrigued by Sen. Obama's message. It's a message that is very similar to the one Gov. Bush ran on in 2000, and won on, promising to bring bi-partisanship and honesty and integrity to Washington." ()
Earlier on Thursday, McClellan told NBC's "Today" show that although he had worried about the rush to war in Iraq, he felt affection for President Bush and trusted his foreign policy advisers.
"My beliefs were different then. I believed the president when he talked about the grave and gathering danger from Iraq," McClellan said. He was deputy press secretary during the lead-up to the war.
McClellan said he has come to believe the war was a mistake but still doesn't think the president lied to oversell the threat from Iraq. "He came to convince himself of that," McClellan said of Mr. Bush.
McClellan said he isn't accusing administration officials of "deliberate or conscious" lies to the American people, but instead of becoming so wrapped up in trying to shape the story to their advantage that they ignored facts that didn't fit the views they were promoting.
McClellan said he expected the angry response from White House insiders that his book has generated. As the book - "What Happened: Inside the Bush White House and Washington's Culture of Deception" vaulted to No. 1 on Amazon.com's best-seller list Wednesday, Republican critics dismissed him as a turncoat, a sellout and a disgruntled former employee.
McClellan said he wrote the book in hopes of changing the "permanent campaign culture" of Washington - which he said he and Mr. Bush had hoped to change from the White House but instead "got caught up in."
"I'm disappointed that things didn't turn out the way we all hoped they would turn out," McClellan said. "We all had high hopes coming in."
Meanwhile, current and former White House officials continued to fire back at the claims in the book.
"I would not personally participate in a process in which we are misleading the American people, and that's the part that I think is hurting so many of his former colleagues," former White House counselor Dan Bartlett said, also on speaking on "Today." "To think that he is making such a striking allegation against his former colleagues, to me, is beyond the pale."
Secretary of State Condoleezza Rice on Thursday also rejected the allegations at a news conference with Swedish Prime Minister Fredrik Reinfeldt in Stockholm where she is attending an international conference on Iraq.
Rice would not comment specifically on charges made by McClellan, but said Mr. Bush was honest and forthright about the reasons for the war. She also said she remained convinced that toppling Saddam Hussein was right and necessary.
"The president was very clear about the reasons for going to war," she said.
Chief among those reasons was the belief, shared widely before the war, that Saddam Hussein had or was developing weapons of mass destruction, Rice recalled, suggesting the international community shouldn't have backed harsh sanctions against Iraq if it doubted the threat.
"I am not going to comment on a book that I haven't read," she said, referring to McClellan's scathing memoir, "but what I will say is that the concern about weapons of mass destruction in Saddam Hussein's Iraq was the fundamental reason."
"It was not the United States of America alone that believed that he had weapons of mass destruction that he was hiding," Rice said, dismissing suggestions that the administration knew the intelligence was incorrect.
"The story is there for everyone to see, you can't now transplant yourself into the present and say we should have known what we in fact did not know in 2001 and 2002," she said. "The record on weapons of mass destruction was one that appeared to be very clear."
Those who were skeptical should have spoken up at the time and argued against U.N. sanctions such as the oil-for-food program, she said.
"The threat from Saddam Hussein was well understood," Rice said. "You can agree or disagree about the decision to liberate Iraq in 2003, but I would really ask that if you ... believe he was not a threat to the international community, then why in the world were you allowing the Iraqi people to suffer under the terms of oil-for-food."
The heart of the McClellan book concerns Mr. Bush's decision to go to war in Iraq, a determination McClellan says the president had made by early 2002 - at least a full year before the invasion - if not even earlier.
"He signed off on a strategy for selling the war that was less than candid and honest," McClellan writes in the book.
McClellan says Mr. Bush's main reason for war always was "an ambitious and idealistic post-9/11 vision of transforming the Middle East through the spread of freedom." But Mr. Bush and his advisers made "a marketing choice" to downplay this rationale in favor of one focused on increasingly trumped-up portrayals of the threat posed by the weapons of mass destruction.
The White House responded angrily Wednesday to McClellan's memoir, calling it self-serving sour grapes.
"Scott, we now know, is disgruntled about his experience at the White House," said current White House press secretary Dana Perino, a former deputy to McClellan. "We are puzzled. It is sad. This is not the Scott we knew."
Perino added that the president was "surprised" by McClellan's assertions. "He is puzzled, and he doesn't recognize this as the Scott McClellan that he hired and confided in and worked with for so many years," Perino said, adding that Mr. Bush was "disappointed that if he had these concerns and these thoughts, he never came to him or anyone else on the staff."
The book provoked strong reactions from former staffers as well.
"Scott himself repeatedly made the case for the war from the podium and even after he left the White House, I remember watching him on Bill Maher's show - about one year ago - making the case for the war," former White House Press Secretary Ari Fleischer wrote in a statement. "If Scott had such deep misgivings, he should not have accepted the press secretary position as a matter of principle."
"For him to do this now strikes me as self-serving, disingenuous and unprofessional," Fran Townsend, former head of the White House-based counterterrorism office, told CNN.
Said former top aide Karl Rove, in an interview with Fox News Channel: "If he had these moral qualms, he should have spoken up about them. And frankly I don't remember him speaking up about these things. I don't remember a single word."
Richard Clarke, another former counterterrorism adviser who also came out with a book critical of administration policy, said he could understand McClellan's thinking, however. Clarke told CNN that he, too, was harshly criticized, saying that "I can show you the tire tracks."
If he had these moral qualms, he should have spoken up about them. And frankly I don't remember him speaking up about these things.
McClellan's book is "nothing but bad news" for Republican presidential nominee-in-waiting, according to CBSNews.com senior political editor Vaughn Ververs.
"The GOP candidate can (and probably will) dismiss McClellan's charges by pointing to the fact that, whatever came before, the war in Iraq continues and he's the one who can bring it to a successful conclusion," Ververs wrote. "But that's not going to make the war - or those who supported it initially - any more popular."