BARACK OBAMA’S Christmas resurrection was so miraculous that even a birther or two may start believing the guy is a Christian.

Nothing captured the president’s sudden reversal of fortune more vividly than the Linda Blair-like head spin of the conservative pundit Charles Krauthammer, who pronounced the Obama agenda “dead” on Fox News on Nov. 3 only to lead the bipartisan media hordes anointing him “the new comeback kid” six weeks later. Last week Obama’s Gallup job approval rating fleetingly hit 50 percent for the first time in eight months. Even in post-shellacking mid-December, polls found that Americans still trusted him more than Washington’s Republican leaders to fix the nation’s ills  health care included, according to the ABC News-Washington Post survey on that question.

As the do-something lame-duck Congress’s triumphs were toted up, the White House pointedly floated the news that the president was meeting with Reagan administration veterans (David Gergen, Ken Duberstein) and taking Lou Cannon’s authoritative biography “President Reagan: The Role of a Lifetime” on vacation. Reagan, of course, was also pummeled (though a bit less so) in his maiden midterms of 1982, then carried 49 states in his 1984 re-election landslide. In January 1983, Reagan’s approval rating was much worse than Obama’s  35 percent. So was the unemployment rate (10.4 percent vs. our current 9.4 percent) as Americans struggled to recover from what was then the deepest economic downturn since the Great Depression.

My poll-crunching Times colleague Nate Silver has already poured cold water on the fantasy that history is fated to repeat itself in 2012. His numbers show zero correlation between presidents’ post-midterms popularity and their fates two years later. But if Obama actually read Cannon, his comeback could have legs. It’s full of leadership lessons that will be particularly useful in outfoxing political adversaries who seem not to have consulted so much as a picture book about the president they claim as their patron saint.