TYSONS CORNER, Va.— As the Republican presidential candidates trek America's political stage, Representative Robert K. Dornan, far back in the pack, stands out as the lounge act of the show. He is the warm-up man and put-down artist tart as Don Rickles, skewering President Clinton as a "draft-dodging adulterer" leading the nation's "cultural meltdown" that a Dornan presidency must reverse.

"I am the one inside the Beltway listening to the screams of the Christians when the lions roar," the Californian Congressman booms in a deep, rough-edged voice that invariably draws cheers from conservative faithful like the Virginia Republicans who gave him a standing ovation last weekend. Even so, their straw poll was delivered solidly to the conservative columnist Patrick J. Buchanan, much as they loved Mr. Dornan's spleenful warm-up act with its warnings against abortion and "pro-active" homosexuality.

He has perfected it across nine terms in Congress in which the aggressiveness of his oratory, flashing lethal and crude as a linoleum knife, has seen him banned from the floor for a day by angry colleagues. He apologizes to none of them, least of all a homosexual Congressman whom he outed on the House floor as having a "revolving door on his closet."

As a politician, Mr. Dornan's forte is pungent speech, what he terms "the courage to be flamboyant." President Clinton may be calling for a new politics of civility, but Mr. Dornan, a master of talk-radio invective, is uninhibitedly calling him "a sleazeball who can't keep his pants on."

He once campaigned against a female primary challenger by warning, "Every lesbian spear-chucker in this country is hoping I get defeated." Amid a dozen firebrand remarks that score a career of political lambasting, Mr. Dornan apologizes for none of his goadings but one -- a House speech in which he denounced Vladimir Posner, the former Soviet propagandist, as a "betraying little Jew."

"That's the only thing in my life I ever lost sleep over," said the Congressman. He insists, he meant to say "Judas," not "Jew," in rebutting the insistence of Mr. Posner that the Soviet Union was free of anti-Semitism.

For this, he ever winces and points to a big Israeli air force belt buckle that he wears like a hair shirt cincture. "I've never been on the House floor that I don't have my Star of David," says the 62-year-old Air Force veteran.

Amid the occasional crash landings of his speechifying, Mr. Dornan is resilient. Orange County Democrats discovered this in last year's Congressional race when they sought to attack him as a moralizing hypocrite who talks family values but was accused of physical abuse by his wife 35 years ago in divorce proceedings that she later dropped. He won re-election easily despite Democratic mailers asking, "Would you vote for a man who beats his wife?"

The airing of this issue along the Presidential trail shows Mr. Dornan at his counter-punching best. First, he notes that his wife, Sallie, who subsequently admitted to emotional instability because of prescription drug addiction and a "dysfunctional" family upbringing, was still at his side as devoted spouse and strategist. Then, the Congressman lists the other divorced and remarried candidates, virtually the entire field, and declares with a big smile: "Excuse me, you're talking about something 35 years ago and, hey, I'm the one married 40 years."

Democrats dismiss him as a practiced "clown" with a nasty mouth. "Right job, wrong planet," says Representative Barney Frank, a gay Massachusetts Democrat wary of his colleague's virulence and "lucid incoherence" in rapid-fire orations. The Congressman whom Mr. Dornan outed on the House floor, Steve Gunderson, a Wisconsin Republican, declines to discuss the incident. Mr. Frank says it was a particularly cruel moment, but Mr. Dornan says it was defensible because he decided Mr. Gunderson was being quietly "pro-active" about homosexuality in discussing legislation.

President Clinton, denounced by Mr. Dornan as having given "aid and comfort to the enemy" during the Vietnam war, responded that the man needs an anti-rabies shot. The Congressman delights in his own campaign-trail riposte: "If he wants to get into veterinarian metaphors he should have been spayed, fixed when he was a young man and maybe he'd get a second term as President."

"I get under their skin," the Congressman says with a smile of satisfaction about the Clintons. "I know because the Secret Service guys tell me."

Other also-rans may well fade by spring, but voters can expect to hear Mr. Dornan still on the Clinton attack well into 1996, carrying the personal issue that larger contenders find risky. "With a vengeance, whether I'm still a candidate or not," Mr. Dornan confirms, deepening his voice with the polish of a talk-radio and television performer.

Indeed, he got to Washington two decades before the current crop of broadcast polemicists starting producing their own candidates.

As a candidate, Mr. Dornan, who is legendary as a House fund raiser in direct-mail small amounts rather than large PAC donations, admits to difficulties on the Presidential circuit. Aiming to have $500,000 by now, he has less than half that and has raised the required $5,000 minimum in only 7 of the 20 states required for matching Federal money in January.

"Bob Dole's lapping the field but his car may hit the wall," Mr. Dornan barks with typical flippancy.

Asked for his Presidential plans, he begins, "I would make my White House closer to Andy Jackson without the bravado and the booze, to John F. Kennedy without squandering precious hours chasing women." He goes on from there, displaying a detail-crammed memory of history and Presidencies. "I would be an exciting President."

Moments later, he can be touching, as when he tells the story of his mother, a red-haired Ziegfield Follies showgirl who was maimed in a car accident. She became a reclusive insomniac devoted to reading political biographies and remains an enormous inspiration for Mr. Dornan 28 years after her death.

"She was gorgeous and she was smart," says the Congressman, who was a movie extra as a young man, encouraged by his uncle, Jack Haley, who played the Tin Man in "Wizard of Oz."

His fans say the news media have trivialized him, but others disagree. "Bob's a willing participant in the image he takes such pleasure in," says Gov. Thomas R. Carper of Delaware, a Democrat who served 10 years in the House and considers Mr. Dornan a friend though they disagreed on basic issues. "He's a patriot, loves our country, and he has a sense of humor about himself," the Governor said, relating a spontaneous family-values joke last April when Mr. Dornan suddenly arrived in Delaware by train to announce his candidacy.

The Governor, who happened to be rehearsing a political lampoon show and was wearing women's clothes, rushed to the station platform. He packed padding under his skirt to look pregnant and printed a sign that proclaimed: "Dornan's the One." The candidate was shrewd enough to not get off the train, staring warily from a window, so the Governor went aboard.

His high point lately is the House's approval of a rollback of President Clinton's executive order that permits abortions at overseas military hospitals. Opposition to abortion is the congressman's keystone in his "cultural meltdown" campaign philippic that ranges to some of the tiniest aspects of Government.

He becomes furious at any equating of the gay rights campaign with the civil rights protests that he marched in as a supporter of the Rev. Martin Luther King Jr. "The road to Selma was not the road to Sodom," he says sternly.

"Homophobia?" he asks in an interview. "I'm not afraid of homosexuals. I love them. Jesus commanded me to love them, just as I love people with a lot of other problems." The gay world, he adds, is not foreign to him. "Remember I grew up in New York and Beverley Hills," he says darkly, telling of being regularly harassed while hitchhiking to his Jesuit high school in West Los Angeles. "Oh, I've been hit on," he says. "And always the same ridiculous line: 'Boy you have nice thighs.' "

Searching for his defining moment, candidate Dornan is the garrulous drummer peddling his best notions ("Faith, Family and Freedom"). His family runs his campaign in clan gatherings free of professionals. "We all know hired consultants can't really tell slime from shinola," he says in blade-sharp dismissal of the larger politics he is up against.

"I pretty well know what's going to happen," he suddenly says, promising his message will be heard if he has to go down fighting, which is to say, talking outrageously.

Photo: Wearing rubber gloves, protesters raised their hands as Representative Robert K. Dornan of California testified last week on the Clinton Administration's AIDS training program. The protesters were upset because White House security officers had worn rubber gloves the previous week while searching men and women as they entered the White House for a conference on AIDS issues. (Associated Press)