The era of celebrity endorsements ended some time ago. We no longer buy the shaving cream that Derek Jeter tells us to use; nor do we vote as some Hollywood actor suggests. We have come to assume that political endorsements are often the product of partisan loyalty rather than any particular standard of merit and that commercial testimonials come only in exchange for cash.

But Oprah’s endorsement of Sen. Barack Obama (D-Ill.) is truly unique and will have a profound impact on the presidential race. She transforms a candidacy into a movement and will increase his momentum from a growth curve to a surging wave.

Oprah sends a message to all American women that it is OK not to vote for Hillary and one to African-Americans that they need to vote for Obama.  Were Oprah seen primarily as a black leader, her endorsement of a candidate of her own race running against one of her own gender wouldn’t mean that much. If her reputation were one for putting her race constantly ahead of her gender, her endorsement of Obama would seem automatic. But that is not who Oprah is.

She is iconic to women of all races; to them she’s a woman who is black, not a black who is female. So her refusal to endorse a fellow female seeking the presidency is tremendously significant to women voters. She sends a message by her unusual intervention in a political contest in which a woman is running. It reads: A woman, yes. This woman, no.

Oprah’s embrace of Obama’s message of change stamps his campaign mantra as legitimate and turns experience into a disqualification rather than an attribute for Hillary. That this much-admired woman would turn against Hillary in order to seek change in Washington lifts Obama to JFK proportions even as it pins on Hillary — to her detriment — the Nixon slogan of 1960: “Experience counts.”

But to black voters, Oprah’s endorsement, precisely because it flies in the face of her gender, is especially significant. The message it sends to African-Americans is: It’s time. Her foray into politics to endorse Obama makes it clear that his candidacy has special relevance to all black men and women everywhere. It is not so much that she has reached into politics to back Obama as that the senator’s candidacy has such meaning for any citizen who is black that it reaches into Oprah’s life and demands that she come forth to support it. Her endorsement seems to suggest that just as anti-Catholic bigotry went away when John Kennedy was elected, so racism may fade in the aftermath of an Obama presidency.

Oprah’s backing also helps tilt the balance of power to Obama and away from John Edwards. Two challengers would have much less chance of beating Hillary than one would in a straight-on battle. But Obama and Edwards sound so much alike that it is hard to distinguish for which one to vote. Oprah’s endorsement almost anoints Obama as the challenger.

Finally, we must recognize that this is truly the first Christmas campaign, conducted not only against the harsh backdrop of news coverage but on a stage also festooned with holiday cheer. Now, in addition to the flag as a prop for campaigning, we have reindeer and Santa. Oprah is from the world of Christmas — mystical, cheerful, appealing, even beguiling. She is no policy wonk but is cast well as a black, female St. Nick bringing joy to the world. Her endorsement softens Obama, wraps him up, and makes of him a Christmas present to America.

Morris and McGann, husband and wife, have written several books together, including Rewriting History, a rebuttal to Living History by Sen. Hillary Rodham Clinton (D-N.Y.). To get all of Dick Morris’s and Eileen McGann’s columns for free by email, go to www.dickmorris.com.