Oprah Winfrey has a magic touch. Everything she endorses seems to turn to gold, whether it's a book or a product. Now she will find out if her unprecedented commercial influence extends to politics, as Jocelyn Noveck reports for the Associated Press:

And now Winfrey's "favorite senator," Barack Obama, hopes the O Factor will work for him, too, as the talk-show host and media icon prepares to campaign for the presidential candidate in the early voting states of Iowa, New Hampshire and South Carolina.

But can Winfrey's influence, vast as it is, extend to the political realm? That depends on whether celebrity endorsements, so courted and coveted in modern politics, really mean much at all in the end. But then again, how many celebrities have the reach and the power of Oprah Winfrey?

"Oprah's in a category of her own," says Todd Boyd, professor at the University of Southern California's School of Cinematic Arts. "She's not a movie star. She's not a rock star. She's a brand. She's one of the few people in the world who can be identified only by one name."

And yet, with all that, you can't necessarily extrapolate to politics, says Boyd. "You could argue that she didn't get to be popular by being political. Politics has never been a big part of her persona. This is not a slam dunk."

Read it all at the link above, and also Myrna Blyth's take at NRO. Obama has suddenly gained momentum over the last month, ever since Hillary Clinton's evasiveness at the Philadelphia debate at the end of October opened the "electability" chink in her Armor of Inevitability - particularly in the key early-voting states of Iowa and New Hampshire. Bringing in a genuine superstar like Oprah could help keep that fire stoked.

Meanwhile, Hillary was endorsed by Barbra Streisand.

Streisand can still sing rings around Winfrey, but political persuasion involves speech, not song. When Barbra opens her mouth to discuss politics (or anything but singing and making movies), she comes across as, well, inarticulate, to be kind. Of course, Hillary does still have the World's #1 Political Superstar (for Democrats and left-leaning independents, at least) in former President Bill Clinton, who will be spending more time in Iowa between now and January 3rd than any rational person with a choice would.

In truth, endorsements rarely turn elections - at least according to interviews with voters after the fact. But in a close race, it certainly doesn't hurt to have a popular celebrity in your corner.