WASHINGTON — President Bush "rarely was the voice of realism" on the Iraq war and "too often failed to lead," according to a new book by Bob Woodward examining how the president handled the war effort during some of the conflict's most difficult years.

Woodward's book, "The War Within: A Secret White House History, 2006-2008," told of a president detached, tentative and slow to react to the escalating violence in Iraq, The Washington Post reported on its Web site Thursday night. But once Bush decided that thousands of additional troops were needed, he moved with focus and determination even though top military advisers resisted him, wrote Woodward, a Post assistant managing editor.

The book is the fourth by Woodward to examine the inner debates of the Bush administration and its handling of the wars in Iraq and Afghanistan. It was scheduled for release Monday.

Spokesman Blair Jones said the White House had no immediate comment.

The book looks at Bush's leadership and governing style based on about 150 interviews Woodward conducted with key players in the administration, intelligence and military establishment. It examines struggles in the administration to deal with growing problems in Iraq during the summer and early fall of 2006. Bush was not getting an adequate picture from his aides of the level of problems in Iraq, Woodward concludes.

Gen. George W. Casey Jr., the commander of forces in Iraq from 2004 to 2007, thought that Bush did not understand the very nature of the war in Iraq and that he focused too much on body counts as a measure of how the conflict was going.

Woodward's book tells of a growing rift between civilian and military leaders, who thought they would be blamed for failure in Iraq.

It says Casey and Gen. John P. Abizaid, then head of U.S. Central Command, opposed the large surge of troops the president ultimately ordered. Only the National Security Council staff strongly supported the surge plan.

Bush turned many of the details of decisions about the war over to National Security Adviser Stephen Hadley, the book says. "Let's cut to the chase," Bush told Woodward. "Hadley drove a lot of this."

The book says the so-called surge of nearly 30,000 additional U.S. combat forces and support troops to Iraq was not the primary factor behind the steep drop in violence there during the past 16 months. Rather, new covert techniques helped locate and kill insurgent leaders and key members of extremist groups such as al-Qaida in Iraq.

The Bush administration spied extensively on Iraq's Prime Minister Nouri al-Maliki and others at the top of the Iraqi government, according to the book.