Fox News turns 10 this week, and it has every reason to celebrate. Launched by media tycoon Rupert Murdoch and former political consultant Roger Ailes as a refuge for viewers fed up with real or perceived liberal bias elsewhere in the media, Fox is the undisputed ratings champion of cable news.

It's been trouncing CNN, MSNBC and CNBC for years, and it sometimes draws a fatter audience share than all its competitors combined, though viewership has slumped a little of late. Pugnacious Bill O'Reilly and conservative tough guy Sean Hannity have become two of the nation's most powerful broadcasters thanks to this kind of ratings pull. Fox is the news media success story of the past decade.

Liberals aren't celebrating the channel's birthday, though. Even before an angry Bill Clinton challenged "Fox News Sunday" anchor Chris Wallace a couple of weeks ago, accusing him of "a nice little conservative hit job" after getting pressed about his record on fighting al-Qaida, Democratic pols and advocates have relentlessly attacked the cable network, accusing it of being a Republican propaganda mill.

Al Gore has likened Fox to a right-wing "fifth column." Leftist groups, including MoveOn.org, funded the documentary "Outfoxed," which purports to expose the channel's nefarious Republican agenda, and petitioned the Federal Trade Commission to ban Fox's use of its famous "Fair and Balanced" slogan as deceptive advertising.

"When a news outlet is allowed to blur the lines between opinion and journalism and call it 'fair and balanced,' I think it's confusing to consumers of information in this country, and it's dangerous to democracy," fretted an official at Common Cause, one of the organizations joining the petition. Hollywood celebrities never miss an opportunity to bash "Faux News."

What explains all this hysteria? Success, of course.

The propaganda charge is unfair, at least when it comes to the network's presentation of news. In the 2004 presidential race, Fox pollsters consistently underestimated President Bush's support. In its final pre-election poll, Fox had Kerry winning by a couple of points, one of the only polls to show the Democrat on top. I'm not sure a right-wing fifth column would do that.

A recent comprehensive study by the University of California Los Angeles political scientist Tim Groseclose and University of Missouri at Columbia economics professor Jeffrey Milyo found Brit Hume's "Special Report" — Fox's most straightforward news show — more centrist than any of the three major networks' evening newscasts, all of which leaned left.

The program is a model of smart news television.

And although it's true that the network's opinion shows (as opposed to its news shows) are, as they're supposed to be, noisily opinionated, it's equally true that Fox's biggest star, O'Reilly, is no mainstream Republican. He regularly charges the oil companies with price-gouging and attacks big business for squashing the little guy. And who can say what host Greta Van Susteren's politics are? She mostly zeroes in on lurid murder mysteries and scandals.

Liberals troop into and out of the Fox studios every day — some of them, like host Alan Colmes and news analyst Marvin Kalb, affiliated with the channel. There's no doubt, of course, that Fox News is more conservative than CBS or CNN. But, after all, that was its founding mission.

Fox's real ethos is not Republican but anti-elitist — a major reason it connects with so many Americans and annoys so many coastal elites. "There's a whole country that elitists will never acknowledge," Ailes once observed. "What people resent deeply out there are those in the 'blue states' thinking they're smarter."

This anti-elitism shows itself in Fox's pro-U.S. stance in covering the Afghanistan and Iraq wars and its broadcasters' use of terms such as "terrorist" instead of "militant" to refer to ... well, terrorists. Since the Vietnam War era, mainstream journalists have tended to see such blunt language and side-taking as unsophisticated, a betrayal of journalistic objectivity.

Another aspect of Fox's anti-elitism: Christians, far from being seen as lunatics or curiosities — as too often is the case in the mainstream media — actually get some respect.

What really frustrates liberals about Fox, though, is simply that, along with talk radio and the conservative blogosphere, it has helped shatter the left's near-monopoly on news and information.

Fox's opinion-driven programming gives conservatives and liberals a chance to get a hearing for their ideas. But Democratic politicians and activists who go on Fox also must defend their views, often against tough questioning, something that happens less often on the networks, where most journalists are left-of-center, survey after survey has shown.

Even more significant, Fox came on the scene a decade ago as a professional news organization that could define and report news as something different from what the elite consensus says it is. To take one of many examples, the corruption of the United Nations' oil-for-food initiative in Iraq, initially downplayed by the mainstream media because of their sympathy for internationalism, was uncovered — deemed newsworthy — on Fox.

All this wouldn't matter if Fox News wasn't so influential. But it is. According to the Pew Research Center, more than 20 percent of Americans now claim to get news from it, and lots of them (37 percent) are Democrats or independents. The network's success also has sparked a "Fox effect," leading some competitors to become more open to right-of-center opinions: MSNBC's "Scarborough Country," hosted by former Republican congressman Joe Scarborough, is a prime example. Until a few years ago, Democrats never had to deal with all these mediatized conservatives.

Nothing would please liberals more than to drag the nation back to the days when The New York Times and CBS News determined what was newsworthy. A group of congressional Democrats has warned Fox to end its supposed anti-Democratic bias — or else. Should Democrats retake Congress, an effort to shut down, or at least muzzle, Fox is far from inconceivable, creepy and illiberal as that sounds.

Something Fox News doubtless is keeping in mind as it pops the champagne corks this week.

Bryan C. Anderson is senior editor of City Journal and author of "South Park Conservatives: The Revolt Against Liberal Media Bias."