One of the most audacious acts playing in the shadow theater of Capitol Hill stars two aides to conservative Sen. Jesse Helms (R-N.C.). cThey are a southern-fried Rosencrantz and Guildenstern battling the red meanies of the political left.

John Carbaugh, 34, baby-faced nemesis of President Carter's foreign policy planners, is the flamboyant one, a strategist who thrives on action, pubilicity, personal contacts, even with the liberal press, and who by his own account never misses a chance to deal directly with foreign head of state.

And James Lucier, 44, "inside man in the skunk works," as he calls himself, or Lucifer as others sometimes refer to him. He is the contemplative one, who prefers to scheme great schemes offstage. He hired Carbaugh.

Last September these two flew to London to sit in on sensitive negotiations on Rhodesia, and the State Department put them in the headlines. Officials accused them of impeding the proceedings by lobbying for their own position. They convincingly denied the charges, with their British hosts backing them up. They had after all had a personal audience with British Prime Minister Margaret Thatcher. a

But some observes say they came close to doing "real mischief."

Since their senator branched out from such issues as abortion, busing and prayer in schools, and into foreign policy, their agenda has been an international Baedeker's tour of rightwing causes. For instance:

They snarled SALT II in the Senate for at least at day with delaying tactics and are planning more of the same.

They claim to have been among those who helped move the issue of the Soviet brigade in Cuba into the headlines.

Though they may stand out in terms of personal style, Carbaugh and Lucier are in the mainstream of a lively Capitol Hill tradition in which staff aides use the umbrella of a member's credentials to agitate and advocate causes.

The two are courtly point men in a conservative operation -- some call it "neoconservative," others dismiss it as the "kook fringe" -- which has found inventive ways to tap large money pools and has effectively adapted an unusual mix of styles and strategies, to achieve its ends. Among its hallmarks are an alliance with fundamentialist Christian "electronic" evangelists and luerative direct mail money-raising. Helms is, among other things, running for vice president.

What Carbaugh and Lucier seek to do with all this apparatus is influence public perceptions and public policy. They try to poke holes in liberal doctrine of all kinds and nudge the country to the right. And they have, a little.

Helms and company "are on the borderline between fringe and serious." said one journalist who covers them. They are winning little victories that portend more."

It was the Helms staff, not the State Department, which last summer brought Rhodesian leaders to this country to introduce them around, at one point using the issue of "freedom" of speech' to pave the way.

They saw early that liberal journalists were vulnerable to an appeal to fairness, and they could hoist them on their own petard," Stephen Rosenfeld, columnist for The Washington Post. "For example, they could argue that [the Rhodesian leader backed by Helms] was more liberal than the [group] toward which the administration was tilting."

Reporters and columnists refer to Carbaugh in the tones of a zoologist describing a rare species -- "the conservative who talks to the press."

He is, they say, an intrepid leaker and planter of news stories and the consensus is that he is both honest and effective, if a bit full of himself. "He takes the fink, and he tries to take the glory," said one.

"Most conservatives are afraid of the media," Carbaugh said over one of the champagne lunches to which he is partial. "I think that is a mistake."

He demurely acknowledges, for instance, that he helped push the issue of the Soviet brigade in Cuba to prominence recently by "putting it before the media until somebody picked it up and ran with it. I became the advocate."

He indignantly denies reports that he sometimes serves intelligence agencies as a conduit to reporters. "Why should I get my hide on the line to give out their kind of stories? I get better information, a more subtle understanding of events by talking to [foreign] leaders myself. I find out things those guys would like to know."

He knew about the Cuba brigade, he said, from talking personally to the heads of state of Guatemala and El Salvador.

On Helms' behalf, Carbaugh said, he has traveled to Brazil, Argentina, Chile, Uruguay, El Salvador, Guatemala, Nicaragua, Haiti, England, Germany, South Africa and Zimbabwe-Rhodesia, some more than once.

Carbaugh noted with a gleam in his eye that he had written his masters thesis on the Logan Act, the law which prohibits private citizens from conducting foreign policy.

The way Carbaugh pays for those plane tickets is also controversial. It is through one of four tax exempt foundations, supported by private contributions, which he and Lucier set up. They also serve as officers.

The three say the insitutes are but poor counterparts of liberal think tanks such as the Brookings Institution and add that a main purpose was to avoid spending taxpayers money on "junkets." The groups serve also as Lucier said, "to preserve key western values."

Helms said the Senate Ethlics Committee, the Internal Revenue Service and "everybody in sight has given the foundations the Good Housekeeping seal of approval.

Helms is able to tolerate Carbaugh's visibility and independence, rare on any congressional stuff because "he is a very confident man," Carbaugh said.

Helms put it somewhat differently, "John's relationship with the press is of his own choosing. He's gregarious by nature. He likes you folks. I indulge him in that . . . Do I occasionally have to rein him in? Frankly, I do."

On the other hand, the senator said Carbaugh's network of personal contacts has often put him "literally weeks ahead of committee staffs in getting information on various issues. He's great at assembling information." g

Carbaugh is "so naive he gets had" sometimes in his dealings with the press, according to Sanford Ungar, managing editor of Foreign Policy journal. "But he's a very engaging character . . . He's about 50 percent as effective as he thinks he is -- and that's pretty damn good."

Carbaugh responded, "This town is full of vaulting egos. It takes a certain amount of self-confidence to live here. Anyway, if I'm just 10 percent as effective as my critics claim I am, I'm happy."

During the turbulent late 1960s, Carbaugh was moving and shaking in the college Young Republicans. He bought a 1968 Rambler, new. By age 23, he had a job in the Nixon White House working on special projects, "not to be confused with the plumbers."

He works long hours and runs, as Helms put it, on "nine parts adrenaline, one part blood." He has a history of falling asleep at the wheel on various campaign trails.

It was during a stint in the office of Sen. Strom Thurmond (R-S-C.) that he first encountered a portly former literature teacher and newsman named James Lucier (pronounced La-SEAR), who also was working for Thurmond.

Colleagues say the two feel a rivalry, sometimes a sharp one, with each other. But they suppress that sitting on either side of a partition in a crowded Senate office suite, like contrasting faces of a ccin, yelling ideas back and fourth over the wall.

Lucier is a "deep thinker whose sense of history is nothing short of remarkable," Helms said.

The senator has known Lucier, he said, since Lucier wrote for the Richmond News Leaders in the early 1960s. Some journalists remember Lucier for inciting, by his own account, the biggest controversy in the paper's history by writing something derogatory about President Kennedy not long after he was assassinated.

Lucier's interest in Africa affairs was evident in his writings about that same period. For "American Opinion," a journal with ties to the ultra-right John Birch Society, he wrote in 1963 about the drift of African leaders toward socialism: abundance without necessitating the earning of it."

And at another point, he wrote of black African leaders who "have learned to grasp only the concept that one eats one's enemies."

"I was a young writer and that was a chance to experiment with creative styles," he says now. "I was trying to amuse, startle, exhort, encourage and so forth . . . It is probably not the mode I would write in today, in a different period."

But he said he would stand by the factual accuracy of the pieces.

Helms, when asked about the items, said he would have to read them in context before passing judgement. But he added, "I believe that about 20 or 25 years ago, the new president of one of those countries was elected not long after he finished serving a term for eating his mother-in-law."

Lucier prefers not to dwell on his own past, but on the historical past. He enjoys pontificating about the views he represents, peopling his talks with references to Ghenghis Khan and Diocletian, Voltaire and Queen Elizabeth.

"We're pre-political here, nonideological," he said. He believes in the ancient Greek idea of personal responsibility, he said, and not in some intellectual plan -- called an ideology -- to be imposed on people.

"Our views represent the way 80 percent of the people feel," he said. "We're just trying to reshape society along the lines people want to live."