AS EVERY CARBON-BASED life form on this planet surely knows, Barack Obama, the junior Democratic senator from Illinois, is running for president. Since making his announcement, there has been no end of commentary about him in all quarters — musing over his charisma and the prospect he offers of being the first African American to be elected to the White House.

But it's clear that Obama also is running for an equally important unelected office, in the province of the popular imagination — the "Magic Negro."

The Magic Negro is a figure of postmodern folk culture, coined by snarky 20th century sociologists, to explain a cultural figure who emerged in the wake of Brown vs. Board of Education. "He has no past, he simply appears one day to help the white protagonist," reads the description on Wikipedia http://en.wikipedia.org/wiki/Magical_Negro .

He's there to assuage white "guilt" (i.e., the minimal discomfort they feel) over the role of slavery and racial segregation in American history, while replacing stereotypes of a dangerous, highly sexualized black man with a benign figure for whom interracial sexual congress holds no interest.

As might be expected, this figure is chiefly cinematic — embodied by such noted performers as Sidney Poitier, Morgan Freeman, Scatman Crothers, Michael Clarke Duncan, Will Smith and, most recently, Don Cheadle. And that's not to mention a certain basketball player whose very nickname is "Magic."

Poitier really poured on the "magic" in "Lilies of the Field" (for which he won a best actor Oscar) and "To Sir, With Love" (which, along with "Guess Who's Coming to Dinner," made him a No. 1 box-office attraction). In these films, Poitier triumphs through yeoman service to his white benefactors. "Guess Who's Coming to Dinner" is particularly striking in this regard, as it posits miscegenation without evoking sex. (Talk about magic!)

The same can't quite be said of Freeman in "Driving Miss Daisy," "Seven" and the seemingly endless series of films in which he plays ersatz paterfamilias to a white woman bedeviled by a serial killer. But at least he survives, unlike Crothers in "The Shining," in which psychic premonitions inspire him to rescue a white family he barely knows and get killed for his trouble. This heart-tug trope is parodied in Gus Van Sant's "Elephant." The film's sole black student at a Columbine-like high school arrives in the midst of a slaughter, helps a girl escape and is immediately gunned down. See what helping the white man gets you?

And what does the white man get out of the bargain? That's a question asked by John Guare in "Six Degrees of Separation," his brilliant retelling of the true saga of David Hampton — a young, personable gay con man who in the 1980s passed himself off as the son of none other than the real Sidney Poitier. Though he started small, using the ruse to get into Studio 54, Hampton discovered that countless gullible, well-heeled New Yorkers, vulnerable to the Magic Negro myth, were only too eager to believe in his baroque fantasy. (One of the few who wasn't fooled was Andy Warhol, who was astonished his underlings believed Hampton's whoppers. Clearly Warhol had no need for the accouterment of interracial "goodwill.")

But the same can't be said of most white Americans, whose desire for a noble, healing Negro hasn't faded. That's where Obama comes in: as Poitier's "real" fake son.

The senator's famously stem-winding stump speeches have been drawing huge crowds to hear him talk of uniting rather than dividing. A praiseworthy goal. Consequently, even the mild criticisms thrown his way have been waved away, "magically." He used to smoke, but now he doesn't; he racked up a bunch of delinquent parking tickets, but he paid them all back with an apology. And hey, is looking good in a bathing suit a bad thing?

The only mud that momentarily stuck was criticism (white and black alike) concerning Obama's alleged "inauthenticty," as compared to such sterling examples of "genuine" blackness as Al Sharpton and Snoop Dogg. Speaking as an African American whose last name has led to his racial "credentials" being challenged — often several times a day — I know how pesky this sort of thing can be.

Obama's fame right now has little to do with his political record or what he's written in his two (count 'em) books, or even what he's actually said in those stem-winders. It's the way he's said it that counts the most. It's his manner, which, as presidential hopeful Sen. Joe Biden ham-fistedly reminded us, is "articulate." His tone is always genial, his voice warm and unthreatening, and he hasn't called his opponents names (despite being baited by the media).

Like a comic-book superhero, Obama is there to help, out of the sheer goodness of a heart we need not know or understand. For as with all Magic Negroes, the less real he seems, the more desirable he becomes. If he were real, white America couldn't project all its fantasies of curative black benevolence on him.