LOS ANGELES — Oprah Winfrey is still the queen of all media, but her crown is beginning to look a bit tarnished.

The average audience for “The Oprah Winfrey Show” has fallen nearly 7 percent this year, according to Nielsen Media Research — its third straight year of decline.

“Oprah’s Big Give,” an ABC philanthropic reality show, beat every program on television except “American Idol” in its premiere week this winter, but steadily lost nearly one-third of its audience during the rest of its eight-week run, according to Nielsen.

The circulation of O, The Oprah Magazine, has fallen by more than 10 percent in the last three years, according to the Audit Bureau of Circulations, and the magazine is seeking a new editor-in-chief after the announced retirement of its longtime steward, Amy Gross.

And while Winfrey still displays a Midas touch when it comes to the endorsement of books and products, some of her latest picks have attracted criticism from longtime fans as she has strayed into New Age spiritualism and, perhaps more dangerous, politics.

Her endorsement of the presidential bid of Sen. Barack Obama appears to have alienated some of the middle-aged white women who make up the bulk of her television audience, many of whom support Sen. Hillary Clinton.

“Not too long ago, she was like the pope,” rarely criticized by her ardent supporters, said Janice Peck, an associate professor of mass communication at the University of Colorado and the author of “The Age of Oprah,” a new book on Winfrey’s cultural influence.

Since the endorsement, however, angry criticism of her political stance became a regular feature of the message boards on Oprah.com, Peck said. “There are a lot of her fans who are not Democrats or who support Hillary Clinton who feel betrayed,” she added.

Market forces

The weaker ratings come as Winfrey is embarking on what is perhaps her biggest project yet: the startup of OWN: The Oprah Winfrey Network, a cable channel being created jointly with Discovery Communications. Its programming, though it will not include “The Oprah Winfrey Show,” which is under contract with current stations through 2010, will entirely reflect Winfrey’s vision of what she calls empowering programming.

Tim Bennett, the president of Harpo Productions, Winfrey’s primary business venture, said in an interview that all aspects of her business are thriving and disputed the idea that her political endorsement had caused problems.

The audience for her daytime talk show, he noted, remains roughly one-third larger than the next most popular competitor, “Dr. Phil,” featuring Dr. Phil McGraw, who was introduced to the talk-show world by Winfrey herself.

Any drop in her television ratings can be traced to general weakness in the overall television audience, Bennett said. Her political endorsement, which has never been highlighted on her syndicated talk show, has not generated any negative feedback from the stations that broadcast the program, he added.

“Those stations pay us a lot of money for that show, and if they felt she was doing anything that was diminishing the mother lode, we would get a call saying, ‘Enough,’” Bennett said. “We didn’t hear one iota of feedback.”

Winfrey was in South Africa last week and was unavailable for comment, her company said. She was there interviewing candidates to oversee the Oprah Winfrey Leadership Academy for Girls, a school she built and sponsors there.

That school itself generated negative publicity for Winfrey last year, when a dorm matron at the school was accused of abusing six students over four months. A trial of the former employee, who has denied the abuse charges, is scheduled in July.

Bennett also disputes the idea that Winfrey might be suffering from overexposure, even though she has recently expanded her empire with a satellite radio show, a network-television Oscar special, and a deal with Discovery Communications to start her new cable venture.

“I’ve never witnessed someone more in touch with the audience she serves,” he said. “She paces herself very well.”

Smaller audience

Both Bennett and Stephen McPherson, the president of ABC Entertainment, said that a second season of “Oprah’s Big Give” would have been a shoo-in for ABC’s prime-time lineup.

“We loved that show and absolutely would have loved to bring it back,” McPherson said, addressing reporters this month at the announcement of ABC’s fall schedule. “But it was something she didn’t want to do.”

The first episode of “Oprah’s Big Give” attracted 15.7 million viewers, according to Nielsen, second that week only to “American Idol,” which drew about 27 million. But it averaged only 11.1 million viewers over eight weeks and finished the season 32nd in total audience among all prime-time programs.

Winfrey’s daytime audience has also declined, to about 7.3 million this year from 7.8 million a year ago and a peak of nearly 9 million in the 2004-05 season. (Those Nielsen figures include viewers who record the show and watch it within seven days.)

Robert Madden, a senior executive vice president at CBS Television Distribution, which oversees the syndication of “The Oprah Winfrey Show,” said he is unworried by that decline.

“It has been the No. 1 talk show for 471 consecutive weeks,” Madden said. “That’s a good barometer if her show is in trouble or not, and obviously if you’re No. 1, you’re not in trouble.”

Certainly Winfrey has demonstrated she can still draw an audience. Her April 3 interview with the “pregnant man,” a female-to-male transsexual whose retained reproductive organs are carrying a child, drew an audience a third larger than the season average.

Though the program has lost nearly one-quarter of its audience of women between the ages of 25 and 54 over the last three years, Madden said current viewership is about equal to where it was 10 years ago, and the recent declines can be tied to the more general falloff in television-watching, particularly among daytime shows.

“Ratings are down just because there are other things people are doing,” he said. Though Winfrey has lost viewers in some markets while “The Ellen DeGeneres Show” has gained, Winfrey’s show has regularly outdrawn DeGeneres’ when the two programs have gone head-to-head.

OWN

Neither does the audience decline worry David Zaslav, chief executive of Discovery Communications, which will start OWN: The Oprah Winfrey Network in the second half of 2009. Her Web site, Oprah.com, will be part of the new venture, and Zaslav noted that fans of Winfrey’s book club downloaded a recent online seminar about her current book pick some 30 million times.

That book pick, “A New Earth,” by Eckhart Tolle, sold faster than any of the previous 60 selections of “Oprah’s Book Club.” But it also has attracted some criticism for Winfrey on her Web site, where some of her fans have said that the book’s spiritualist leanings go against Christian doctrine.

“She is endorsing a kind of spirituality that can be offensive to traditional Christians,” Peck, the University of Colorado professor, said.

The circulation of O, the magazine, ticked up by about 1 percent to 2.4 million at the end of last year from a year earlier, but is down from nearly 2.7 million in 2004, according to the Audit Bureau of Circulations. A spokeswoman for Winfrey’s magazine said it had enjoyed five straight years of growth in advertising pages.