The campaign began a push yesterday to deal with its Iraq challenge. Besides her remarks in New Hampshire, Mrs. Clinton submitted a bill in the Senate to block sending more troops to Iraq, though she would not cut off financing. In a new video on her Web site, she called for starting to redeploy troops within 90 days — or else, she threatened, Congress should revoke authorization for the war.

“She is in a box now on her Iraq vote, but she doesn’t want to be in a different, even worse box — the vacillating, flip-flopping Democratic candidate that went to defeat in 2000 and ‘04,” said one adviser to Mrs. Clinton. “She wants to maintain a firmness, and I think a lot of people around her hope she maintains a firmness. That’s what people will want in 2008.”

Indeed, Mrs. Clinton believes that reversing course on her vote would invite the charge of flip-flopping that damaged Mr. Kerry or provoke the kind of accusations of political expediency that hung over Al Gore in 2000 and her and her husband, President Bill Clinton, in the 1990s, several advisers said. She has argued to associates in private discussions that Mr. Gore and Mr. Kerry lost, in part, because they could not convince enough Americans that they were resolute on national security, the associates said.

Mrs. Clinton’s image as a strong leader, in turn, is critical to her hopes of becoming the nation’s first female president. According to one adviser, her internal polling indicates that a high proportion of Democrats see her as strong and tough, both assets particularly valuable to a female candidate who is seeking to become commander in chief. Apologizing might hurt that image, this adviser said.

Mrs. Clinton’s belief in executive power and authority is another factor weighing against an apology, advisers said. As a candidate, Mrs. Clinton likes to think and formulate ideas as if she were president — her “responsibility gene,” she has called it. In that vein, she believes that a president usually deserves the benefit of the doubt from Congress on matters of executive authority.

Yet some Democrats are surprised that the Clinton campaign, which is widely regarded as a ferocious political operation, has not lanced this issue. After all, they said, a majority of Democrats tell pollsters they are against the war, and many Americans want a firm deadline to leave Iraq. Mrs. Clinton has called for capping the troop level, but has opposed a deadline.

“For the life of me I don’t understand why she can’t say, ‘I made a mistake, I was misled, the country was misled, the intelligence was manipulated,’ ” said Robert M. Shrum, a senior adviser to Mr. Kerry in 2004. “I think there’s this tremendous desire in her campaign not to get into a position where you’re identified with traditional Democratic views. But this is now a party that is strongly antiwar, and is desperate for change on big issues like Iraq and health care.”