Michael Savage, the conservative radio host whose hiring by MSNBC has turned him into a national lightning rod, is threatening to lead a boycott against the "slimy, filthy groups" that oppose him.

Accusing them of "Nazism" and "economic terrorism," Savage has told listeners that "these brownshirt groups" live in "mud puddles" and that he may ask the Justice Department to investigate them.

Savage is responding to a letter-writing campaign by the Gay and Lesbian Alliance Against Defamation aimed at pressuring MSNBC into dropping the Savage program, which debuts Saturday. MSNBC executives have agreed to schedule a meeting tomorrow with the group, whose effort is backed by the National Organization for Women.

The contretemps comes as MSNBC, the third-place cable news operation, announced several staffing changes as it gears up for coverage of a likely war with Iraq. Some media critics say the network, which has a news alliance with The Washington Post, is lurching to the right in an effort to compete with top-rated Fox News Channel. In the last few weeks, MSNBC has hired Savage and two former Republican members of Congress, while dropping the liberal Phil Donahue and ending negotiations with left-leaning newsman Sam Donaldson.

MSNBC spokesman Alan Winnikoff, confirming that the network has gotten a slew of negative letters and e-mails about Savage, says: "We're asking people to wait and watch the show before jumping to conclusions."

The bearded, bombastic Savage, whose San Francisco radio show is carried on 305 stations (including Washington's WTNT-AM) is the author of "Savage Nation," a diatribe against "left-wing wackos" that is No. 1 on the New York Times bestseller list.

In an interview, Savage says of his critics: "I don't know how they can censor a show that hasn't aired yet. They're trying to use me as a pawn in a bigger game. . . . It looks like a shakedown to me. It may be a cooking show. How do they know what I'm going to do?"

Asked if MSNBC hired him to appeal to a conservative audience, Savage says: "No doubt about it. They know which way the wind blows."

Ironically, his book lambastes MSNBC as "More Snotty Nonsense By Creeps" and ridicules its anchor Ashleigh Banfield as "the mind-slut with a big pair of glasses that they sent to Afghanistan."

Savage writes of "the degenerates on the left who want to sell Americans on the idea that homosexuality, bisexuality, transexuality, even sex with animals is normal." He complains that a "minority of feminist zealots" has "both feminized and homosexualized much of America." On his show he talks about immigrants from "turd world nations" and called the Million Mom March for gun control the "million dyke march."

GLAAD spokeswoman Cathy Renna says that "to associate what Michael Savage does with journalism is fundamentally wrong. He's into bullying and name-calling. It tarnishes the credibility of a network like MSNBC." Renna says 2,000 people have used her group's Web site to send protest letters to the network.

At the same time, she says, her group has received numerous letters from Savage fans charging "that we're censors and we're the sodomy lobby."

The hiring of Savage, former House majority leader Dick Armey and former GOP congressman Joe Scarborough of Florida was announced as MSNBC was in the process of canceling "Donahue" after just seven months. This has sparked criticism that the network, which has also signed former Minnesota governor Jesse Ventura, is pandering to the right. Donahue said last week he believes MSNBC is trying to "out-Fox Fox" by appealing to conservative viewers.

An internal NBC memo, reported on the Web site AllyourTV.com, said Donahue presented a "difficult public face for NBC in a time of war" while "our competitors are waving the flag at every opportunity," because "he seems to delight in presenting guests who are anti-war, anti-Bush and skeptical of the administration's motives."

In a statement on the Savage flap, MSNBC says the decision "was made with the full awareness of his reputation for controversy and confrontation. We respect the right of those who wish to protest. However, we also strongly defend his new show as a legitimate attempt to expand the marketplace of ideas."

Winnikoff denies any effort to "become more like our unnamed competitor" -- Fox -- saying Ventura is a libertarian and "Hardball" host Chris Matthews is hard to pigeonhole politically. "We're a big tent that encourages perspectives from all ends of the ideological spectrum," he says. Even afternoon host Pat Buchanan, "who's obviously a conservative, is not an establishment Republican."

MSNBC preferred to focus yesterday on efforts to beef up its war team. The network is tapping two former CNN correspondents, sending Peter Arnett to the Persian Gulf and Carl Rochelle to the Pentagon. The 7 p.m. show "Countdown Iraq" will feature reports from NBC mega-stars Tom Brokaw, Tim Russert and Brian Williams. In addition, "NBC Nightly News" weekend anchor John Seigenthaler will handle MSNBC's 9 a.m.-to-noon block with Chris Jansing, while veteran newsman Forrest Sawyer will join Natalie Morales from noon to 2 p.m. and correspondent Bob Kur shifts to the White House.

But such efforts could be overshadowed, at least temporarily, by the Savage controversy. Savage's radio rants, which read harshly in black and white, are sometimes delivered with a sense of humor. But he was not joking in one recent monologue, an audio clip of which is available at www.glaad.org:

"You rats! You stinking rats who hide in the sewers! You think you can go after my income? You think you can kill my advertisers? You think I'm Dr. Laura? You think I'm gonna roll over . . . ? You're wrong. I'm going to find out where you get your money from. You live by handouts, all of you. You live off grants, all of you. You're a bunch of beggars, but you don't know how lucky you are. If you continue this, we're going to go after your funding sources. And we will do everything we can within the legal realm to cut off that funding! We are also going to go to the U.S. Justice Department under John Ashcroft! What you are doing is illegal!"

NOW President Kim Gandy says she was "flabbergasted" by what she calls Savage's "vulgarity" and "hate-mongering. . . . He must be terribly intimidated by women to attack us so viciously. For a major cable network like MSNBC to give him a platform for this kind of hatred of women is more than disappointing. It's sickening."

Steve Rendall, a spokesman for the liberal group Fairness and Accuracy in Reporting, says he offered to appear on Savage's radio show after the host called the group chicken, but was canceled after an initial booking. Savage "really is in many cases a gutter-level bigot," Rendall says. "MSNBC is going across a line here that Fox would hesitate to cross."

But Savage says some of the inflammatory quotes trumpeted by his critics are "eight years old" or "out of context," and "some are said in jest, and they know it."

"It's actually a gay-friendly show," he says. "I'm quite libertarian when it comes to sexuality."

Michael Savage, above left, joins a revamped MSNBC lineup that also includes, clockwise from above right, former Minnesota governor Jesse Ventura and former congressmen Joe Scarborough and Dick Armey. Critics say the cable news channel has jumped far to the right.