NEW YORK -- For all the buzz about the "O Factor" -- what Oprah Winfrey can or can't do for Barack Obama -- there's been little talk about the reverse effect.

Call it the Obama Factor: how a talk show queen's first presidential endorsement might alienate her fans.

Oprah's audience isn't necessarily an Obama crowd. They tend to be older, less educated women who are home to watch her show at 4 p.m., says Andra Gillespie, political science professor at Emory.

Gillespie says those fans are more likely to support his rival Democrat, Sen. Hillary Clinton.

Some Oprah watchers are expressing their disapproval at Oprah.com. "Oprah, please don't go around the country supporting Obama, it is a real turn off for a lot of your fans," one person wrote. Another said, "Too many people are fascinated with entertainers and actually think that your opinion matters."

Winfrey has also been accused of stumping for Obama only because he is black. She responded to those comments, telling Diane Sawyer, "To think that I would be supporting someone just because of their skin would mean we haven't moved far from Dr. King's speech in 1963, where he said we should be judged by the content of our character not the color of their skin."

Party of one

Obama's likability could be key to maintaining Winfrey's. If she had chosen a more polarizing figure, there could be worse consequences, said Marc Lamont Hill, professor of urban education and American studies at Temple.

Hill noted Winfrey has continued to present herself as a nonpartisan person, saying she has voted for as many Republicans as Democrats. At the same time, she's left her message happily vague.

"If she said, vote for Obama, the troops need to come home, No Child Left Behind is bad, the war on drugs is a fraud, that's when you're going to start seeing the ratings drop," says Hill. "She talks in very general terms. 'Americans need a change,' which just about every American believes."

Ratings information for the week after Winfrey's political debut won't be out until Tuesday, but "The Oprah Winfrey Show" is in reruns through December, meaning viewership typically dips.

While Oprah owes some of her extraordinary popularity to a sense of inclusiveness, her political leanings haven't been much of a secret.

"Most of her fan base has a pretty good idea of what her politics are," says Robert Thompson, founding director of the Bleier Center for Television and Popular Culture at Syracuse University. "It's not as though she has endorsed someone who is counterintuitive to what her whole message has been about."

Minor disappointment

Still, Winfrey has plenty of Republican fans, including Lorin Crenshaw, vice president of Republicans for Black Empowerment. Crenshaw was frustrated that Oprah would support any Democrat.

"Oprah's endorsement represents a disconnect to me between what the community needs and her motives, which are likely strategic and brand oriented," he says. "More than a black president, what black America needs are an economic environment that is conducive to optimal job creation and a radical reform of the public school system, and in both instances Obama is not the guy."

Crenshaw thinks the fallout to Winfrey's TV show and magazine will nonetheless be minimal. Winfrey, he says, is not risking a lot because people don't think she is going to change the outcome of the election.

It's an open question whether Winfrey can influence the election. According to a recent New York Times/CBS News poll, only 1 percent of Democrats polled reported that Oprah's endorsement would make them more likely to support Obama, while 14 percent said they would be less likely to vote for the candidate because of Oprah's support.

On the other hand, another poll by the Pew Research Center for the People & the Press found that Winfrey's support had increased Obama's visibility and that more than 60 percent thought it would help his campaign.

Still Oprah

Even though she doesn't agree about politics, Frances Rice says she is still an Oprah fan.

"I understand that she is a liberal," says Rice, chair of the National Black Republican Association. "I have always known that. She's an American citizen and she can endorse whomever she pleases. She tries to get people to change their lives and that I appreciate about her. I just don't share her political perspective."

Politics probably won't ever become the thrust of her show, says Debora Thomsen, a retired professor and realtor in Washington state. Oprah herself has said she is not going to do political commercials, and that she has pretty much done her part.

"I think endorsing Obama is sort of a sideline," says Thomsen.

Linda Block, a feng shui practitioner and Obama supporter outside of Denver, is praising Oprah's new political involvement.

"If she was choosing any candidate, I think that's her right and privilege," says Block. "Good for her. That's what I say."