“You had a Rudy Giuliani who wound up not being really competitive, and you had a candidate who emerged on the right,” said Carl Forti, the Romney campaign’s political director. “When a candidate emerged on the right and with no one to check McCain on the left, it gave him more room to grow, and we were in the middle.”

Image Mitt Romney with Ann Romney at a conservative conference on Thursday in Washington. He tried to become a Reagan-like figure through issues like abortion rights and gun control. Credit... Stephen Crowley/The New York Times

But in an election cycle in which authenticity is an overriding concern among voters, the perception of Mr. Romney remaking himself into a Reagan-like figure through his positioning on issues like abortion rights and gun control exposed him to biting, often mocking attacks from his rivals, who were almost universal in their scorn of him. His fellow Republicans used the flip-flopping accusations to reframe everything he did. Even in the final hours of Mr. Romney’s candidacy, Mr. McCain was running advertising suggesting Mr. Romney had shifted radically in his view of Ronald Reagan.

The authenticity issue was a problem his advisers recognized early on. As Mr. Romney was laying the groundwork for his run back in 2006, Alex Castellanos, one of the campaign’s chief media strategists, put together a 77-slide PowerPoint presentation, first reported by The Boston Globe, which listed some of Mr. Romney’s vulnerabilities, including the perception of him as an ideological panderer, as well as his Mormonism and his inexperience in military affairs.

But his advisers perceived there was a gap in the field for an electable conservative and pounced on that opportunity in recasting Mr. Romney’s image. They believed that he could overcome the more moderate views he had espoused in the past as governor of Massachusetts and while running for the Senate in 1994 against Edward M. Kennedy by being up front about his most obvious change on abortion. They also spotlighted Mr. Romney’s family, arguing he lived his values and that examining his beliefs up close would reveal that his inner convictions were conservative.

“Ultimately, we thought if we put everything into the crucible, people would say, ‘Wait, this guy is conservative, and he’s honest and straightforward,’ ” said Alex Gage, Mr. Romney’s director of strategy.

But Mr. Gage acknowledged that in Mr. Romney’s rush to beat back the attacks questioning his conservative credentials, he may have swung too far in the other direction, ultimately taking some of the most-pronounced stands against illegal immigration and social issues.

“Maybe we overcompensated,” Mr. Gage said.

Competing against far better-known candidates, the campaign’s strategy from the beginning was to “win early and often,” backed by an unprecedented early advertising strategy that resulted in the campaign spending more than $30 million on television commercials.