Matt Drudge's public eruption at Fox News Channel is about to cost him his television career.

In a letter, Fox News has threatened to sue the Internet columnist for refusing to tape his weekly talk show Saturday after being told that he could not brandish a picture of a 21-week-old fetus. Network sources say he is on the verge of being fired.

Fox attorney Dianne Brandi wrote Drudge that "you flatly refused to perform the services under your agreement. . . . You made disparaging, false and defamatory remarks about Fox News," calling his conduct "completely unprofessional and unacceptable." The letter says that "it is necessary for you to apologize to Fox News" to avoid the possibility of a "breach of contract lawsuit."

But Drudge was not in an apologizing mood toward Rupert Murdoch's network yesterday. "Over my dead Web site!" he declared. "Seems to me Murdoch has enough money, he doesn't need Drudge money. . . . Some of these overgrown fetuses at Fox hit the panic button."

Said Fox News President Roger Ailes, who hired Drudge: "He wants to apply Internet standards, which are nonexistent, to journalism, and journalism has real standards. It can't work that way."

The Washington Post reported Monday that Drudge had refused to do the program after being told that he could not show a National Enquirer photo of a tiny hand emerging from the womb during a spina bifida operation on the fetus. Drudge, who opposes abortion, wanted to use the picture to talk about why the United States should not help finance U.N. population-control programs. Network executives vetoed the idea, saying that would amount to misrepresenting the photo.

"I apologize to Fox News for having an open mind," Drudge said. "I've been spoiled on the Internet, I really have. The lack of ability to express my opinion on an issue that's important to me has left me believing the Internet is the future."

Officially, Fox was tight-lipped about Drudge's status. "We were sorry that he did not live up to his contractual obligations," said spokesman Brian Lewis. The Fox attorney's letter reminded Drudge that his contract says he cannot talk about his services for Fox News "without mutual consent," and that final editorial decisions are made by the network.

Brit Hume, Fox's Washington managing editor, said he enjoyed Drudge's "eccentric" show and did not think the cyber-gossip hurt the network's credibility. But, he said, Drudge is now "banging his rattle on the flats of his crib and raising hell. What he calls censorship is what the rest of us call editing."

Fox executives noted that Drudge's ratings had dropped 30 percent since last fall, from 230,000 to 162,000 households, although he is usually the network's highest-rated weekend show. Drudge notes he was moved from 9 p.m. to a more competitive 7 p.m. time slot when his show was expanded to an hour in June.

Still, said one Fox insider, "he hasn't broken news in some time. He might have outlived his 15 minutes of fame."

But Drudge was still milking those minutes yesterday, talking about the showdown on Rush Limbaugh's radio show. Drudge points out that Oprah Winfrey showed footage of the spina bifida operation on her syndicated program this week.

Two Fox executives said Drudge may have precipitated the blowup to get out of the final year of his contract. Drudge has tired of the show and takes in far more in advertising revenue from his Internet site than under his Fox deal. He insists, however, that the photo flap is a matter of principle and that Fox was more permissive in allowing him to report on the Clinton White House scandals.

The tantrum didn't take place in a vacuum. According to Fox staffers, Ailes told Drudge in a recent meeting that he was "phoning it in" and "booking the same old people," leading to the ratings slide.

In a second meeting with Ailes, Drudge says he asked to be let out of his contract but agreed to continue. "He begged me to stay," said Drudge. "He said, 'You're my top show, I need you.' " But Fox staffers say Ailes simply reminded Drudge that he was legally obligated to complete his contract.

CAPTION: Matt Drudge, sorry? "I apologize to Fox News for having an open mind," he said.