By that standard, dialing back on matters like abortion legislation or gay rights is not really a threat to the president, no matter how much it might rile his supporters on the political left. For one thing, Mr. Obama has already conditioned the public to understand that his views on such social issues are complex; he is, after all, the candidate who campaigned as a “fierce advocate” of equality for gays and lesbians, while at the same time opposing gay marriage.

But detainee policy is another matter; it goes to the core of Mr. Obama’s very being as a politician. A central premise of his campaign was his pledge to restore America’s moral standing in the world by undoing the anti-terrorism policies of his predecessor, Mr. Bush. Now, with his embrace of military commissions and his decision on the detainee photos  as well as a fresh proposal, outlined in last week’s speech, for “prolonged detention” of terrorism suspects who cannot be tried  Mr. Obama is drawing comparisons to Mr. Bush by critics, who say he has backtracked, in subtle yet important ways, from the positions he staked out as a candidate.

The White House is well aware of such criticism, and it is one reason Mr. Obama went to the National Archives last week. His senior adviser, David Axelrod, said the intent was for the president to explain his approach to a complicated array of legal and national-security challenges. “There is an awful lot of misunderstanding out there,” Mr. Axelrod said.

Image Credit... Nicholas Kamm/Agence France-Presse — Getty Images

So Mr. Obama tried to set the record straight, drawing on his skills as an orator and a former constitutional law professor. He painted, in broad strokes, his philosophy that upholding American values is central to defending the United States. But aside from the lofty rhetoric, he also used the speech, in a very nitty-gritty way, to rebut criticism on matters like his refusal to release detainee photos while making the interrogation memos public.

“Now in the press’s mind, and in some of the public’s mind, these two cases are contradictory,” Mr. Obama said in making his case. “They are not to me.”

Mr. Obama argued that there was no danger in releasing the legal memos, because the existence of the interrogation techniques was widely known, and he had already banned them. But while his Justice Department had initially agreed to make the photos public, the president said, his national security team persuaded him that the images would “inflame anti-American opinion,” putting troops in harm’s way. “In short,” the president concluded, “there is a clear and compelling reason not to release these particular photos.”