President George W. Bush considered dumping Vice President Dick Cheney from his 2004 reelection ticket to dispel the myths about Mr. Cheney’s power in the White House and “demonstrate that I was in charge,” the former president says in a new memoir.

The idea came from Mr. Cheney, who offered to drop out of the race one day during a private lunch between the two men in mid-2003. “I did consider the offer,” Mr. Bush writes, and spent several weeks exploring the possibility of replacing Mr. Cheney with Senator Bill Frist of Tennessee, the majority leader, before opting against the switch.

“While Dick helped with important parts of our base, he had become a lightning rod for criticism from the media and the left,” Mr. Bush writes. “He was seen as dark and heartless – the Darth Vader of the administration.” The president resented the caricature that Mr. Cheney really controlled the White House. “Accepting Dick’s offer would be one way to demonstrate that I was in charge,” he writes.

But in the end, Mr. Bush writes, “the more I thought about it, the more strongly I felt Dick should stay. I hadn’t picked him to be a political asset; I had chosen him to help me do the job. That was exactly what he had done.” Mr. Bush wrote that he trusted Mr. Cheney, valued his steadiness and considered him a good friend. So, “at one of our lunches a few weeks later, I asked Dick to stay and he agreed.”

Mr. Bush discloses the episode in a new book, “Decision Points,” to be published next week by Crown and obtained on Tuesday by the New York Times. The book and the accompanying media tour will be Mr. Bush’s first major foray back into the public arena after nearly two years of public silence. His reemergence coincides with the political resurgence of Republicans who were poised to make substantial gains in Tuesday’s midterm congressional elections.

The book may help Mr. Bush define his legacy in more favorable terms after leaving office with some of the lowest approval ratings in modern times. With his successor, President Obama, now mired in his own troubles and facing voter repudiation, Mr. Bush’s circle hopes the public will come to view the former president more sympathetically over time. But in keeping with his desire not to complicate Mr. Obama’s stewardship, Mr. Bush says almost nothing about his successor’s actions other than to praise him for sending more troops to Afghanistan.

Like his father, Mr. Bush chose not to write a traditional birth-to-Oval-Office autobiography, but instead selected 14 major decisions, or clusters of decisions, that shaped his life and presidency, such as the moment he quit drinking and his handling of the attacks of Sept. 11, 2001.

For the most part, Mr. Bush offers a strong defense of his presidency, declaring that his decision to invade Iraq was the right one because “America is safer without a homicidal dictator pursuing” biological or chemical weapons and “the Iraqi people are better off with a government that answers to them instead of torturing and murdering them.”

He likewise defends his decision to authorize harsh interrogation techniques on captured terror suspects. When the C.I.A. asked him if they could subject Khalid Sheikh Mohammed, the Sept. 11 mastermind, to a form of simulated drowning called waterboarding, he writes that he said, “Damn right.” The interrogations, he adds, “saved lives.”

At the same time, he offers a more expansive self-critique than he did while in office, expressing regrets for his slow response to Hurricane Katrina, his acquiescence to reducing troops in Iraq after the initial invasion and his decision to nominate his friend and lawyer, Harriet Miers, to the Supreme Court. He had “a sickening feeling” when he learned there were no mass destruction weapons in Iraq and said “cutting troop levels too quickly was the most important failure of execution in the war.”

He also provides his first extended account of the internal debates that shaped his time in office. For example, he recounts that intelligence reports in mid-2002 suggested that Abu Musab al-Zarqawi had a biological weapons laboratory in northern Iraq and prompted a sharp debate about whether to bomb it immediately. Mr. Cheney and Defense Secretary Donald H. Rumsfeld urged him to attack, while Secretary of State Colin L. Powell and the national security adviser Condoleezza Rice convinced him to wait.

While the book is not a score-settling account, he does offer sometimes candid words about people. He “never clicked” with his first treasury secretary, Paul O’Neill, who “didn’t gain my confidence.” He “was angry” at his father’s former national security adviser, Brent Scowcroft, for publishing his opposition to the war in a newspaper rather than telling him directly. He refers to his longtime spokesman Scott McClellan, who later wrote a harsh tell-all book, only as “the White House press secretary” and never by name.

He takes Senator Harry M. Reid of Nevada, the Democratic majority leader, to task for saying during the worst of the violence in Iraq that the war was lost, calling that “one of the most irresponsible acts I witnessed” in Washington. Yet Mr. Reid’s Republican counterpart, Senator Mitch McConnell of Kentucky, privately told the president in September 2006 that he would cost them the election and urged him to “bring some troops home from Iraq.” Ultimately, Mr. Bush did the opposite, and Mr. McConnell agreed.

He also recalls sharp exchanges with other officials. When Senator Mary Landrieu made an “unproductive emotional outburst” during a Katrina meeting, Mr. Bush said he told her, “Would you please be quiet?” He recalls deep frustration that Gov. Kathleen Blanco of Louisiana resisted for days his attempt to send in federal troops with law enforcement powers. He describes arguing over dinner with Cherie Blair, the wife of the British prime minister, about the death penalty.

But it is his relationships with two men, his father and Mr. Cheney, that come through in intriguing slices. For all the speculation about his father’s view of the son’s handling of Iraq and other matters, Mr. Bush reports that the 41st president advised him at Christmas 2002 that if Saddam Hussein would not comply with United Nations disarmament resolutions, “you don’t have any other choice.” The two also exchanged faxed letters of support on the day the younger Mr. Bush ordered the invasion in 2003.

Mr. Bush’s consideration of replacing Mr. Cheney on the ticket has an interesting antecedent. During his father’s ultimately unsuccessful reelection bid in 1992, Mr. Bush says he urged him to dump Vice President Dan Quayle and put Mr. Cheney, then the defense secretary, on the ticket. His father declined, “but I never completely gave up on my idea of a Bush-Cheney ticket.”

Mr. Cheney clearly pushed Mr. Bush toward war. The former president writes that his vice president “had gotten out in front of my position” with an August 2002 speech dismissing the prospect of further inspections and says he ordered Ms. Rice to call Mr. Cheney to rein him back in.

At one point during their private weekly lunch, Mr. Cheney questioned whether Mr. Bush would follow through on the threats against Mr. Hussein. “Are you going to take care of this guy, or not?” Mr. Cheney demanded.

The vice president also disagreed with Mr. Bush’s decision to fire Mr. Rumsfeld after the 2006 mid-term elections with the Iraq war going badly and pushed the president to pardon I. Lewis “Scooter” Libby, the vice president’s former chief of staff who was convicted of lying in the C.I.A. leak case.

While he had earlier commuted Mr. Libby’s sentence, Mr. Bush in his final days in office asked two lawyers to review the case and meet with Mr. Libby but both reported back that they could not justify overturning the conviction. The president writes that he wrestled with the decision in his final weekend at Camp David so much that his wife, Laura, finally told him: “Just make up your mind. You’re ruining this for everyone.”

When he decided against a pardon, Mr. Cheney lashed out at him in private. “I can’t believe you’re going to leave a soldier on the battlefield,” the vice president told him. “The comment stung,” Mr. Bush writes. “In eight years, I had never seen Dick like this, or even close to it.” He worried their friendship was fractured, but writes that it eventually survived the dispute.

So too he hopes the passage of time will improve his own standing in history. “Decades from now,” he concludes, “I hope people will view me as a president who recognized the central challenge of our time and kept my vow to keep the country safe; who pursued my convictions without wavering but changed course when necessary; who trusted individuals to make choices in their lives; and who used America’s influence to advance freedom.”

Julie Bosman contributed reporting.