WASHINGTON - Scott McClellan says he did not set out to write a memoir sharply critical of the White House. A publishing-industry insider described his early concept as "a not-very-interesting, typical press-secretary book."

But somewhere between proposal and publication, as McClellan told it yesterday, the scales dropped from his eyes, leading him to write a book that accuses President Bush and his senior aides of abandoning "candor and honesty" to wage a "political propaganda campaign" that led the nation into an "unnecessary war."

"Over time, as you leave the White House and leave the bubble, you're able to take off your partisan hat and take a clear-eyed look at things," Bush's former press secretary said in an interview. "... I felt at the end it had to be as honest and forthright as possible."

What Happened: Inside the Bush White House and Washington's Culture of Deception

is a scathing critique of the Bush presidency. It vaulted this week to the top of the bestseller lists. It has also led many of McClellan's oldest friends and colleagues to brand him, among other things, a turncoat and a fraud.

McClellan, 40, yesterday portrayed himself as "increasingly dismayed and disillusioned" during the end of his three years as press secretary. He also strongly defended some of the most incendiary allegations in the book, including that Bush was intent on confronting Saddam Hussein from the start of the debate on Iraq and that the White House's "permanent campaign" mode crippled its ability to cope with Hurricane Katrina and other crises.

McClellan and Peter Osnos, the founder of PublicAffairs, the small company that published

What Happened

, rebutted suggestions from some, including McClellan's predecessor, Ari Fleischer - that McClellan may have had a ghostwriter or undergone heavy-handed editing. Fleischer and others have said the book does not "sound like" McClellan, who was known as genial and soft-spoken.

McClellan said that he started focusing on writing the book about a year ago and that the work was especially intense in the last several months as the publishing date approached.

Osnos said McClellan just needed editorial guidance to tell the story he wanted to tell all along. "We are journalists, independent-minded publishers," Osnos said. "We weren't interested in a book that was just a defense of the Bush administration. It had to pass our test of independence, integrity and candor."

Osnos dismissed suggestions that McClellan was merely hoping to cash in. Unlike some larger publishing houses, he said, PublicAffairs almost never pays more than a five-figure advance.

Former colleagues continued their sharp criticism of McClellan yesterday. Secretary of State Condoleezza Rice, in Sweden, said that there was no intent to mislead Americans about Iraq and that Bush "was very clear about the reasons for going to war." And former presidential counselor Dan Bartlett called the book "beyond the pale."