THE ATTRACTIVE WOMAN who answers the door at 325 Constitution Ave., in the shadow of the Capitol, is wearing a red dress with a plunging neckline. She says her name is Darlene Dove.

She invites her visitors to step inside the three-story, red-brick town house. The living room is furnished with a handsome antique desk, comfortable couches and an expensive stereo set, upon which sits a bottle of medium-quality Bordeaux. There are bedrooms upstairs.

This is the headquarters of the Institute of American Relations, just one of the increasingly significant, and well financed, outposts of a growing political empire run by, or in the interest of, Sen. Jessee Helms, the stauchly conservative Republican from North Carolina.

"Jesse Helms is unique," says Herbert Alexander, a leading expert on money and politics. "No one else raises so much money; no one else is so deep into political high technology. It is the wave of the future."

This senator, who many believe is the second most powerful conservative in the country, and his cause are a study in paradox. While the hero of the Moral Majority crowd is as strait-laced as they come, Jesse Helms is surrounded by a staff that churns and bubbles with bizarre ideas, clashing egos -- and sometimes with plain good spirits.

Sen. Helms himself carefully cultivates the courtly country-boy image. But he is one of the shrewdest and toughest operators in American politics, even to the point of downright meanness, especially on racial matters.

Some of the 59-year-old North Carolinian's power is rooted in the Senate. He is the chairman of the Agriculture Committee, a senior member of the Foreign Relations Committee and the chairman of the Western Hemisphere subcommittee. He also heads the GOP steering committee, a group of about two dozen activist conservative senators.

But Sen. Helms' power has much wider roots. Operating out of North Carolina's capital, Raleigh, in his behalf is the Congressional Club, probably the most potent independent political operation in the country. It raised more than $7 million for the senator's 1978 reelection and raised another $8 million last year to help Ronald Reagan and a number of other conservative candidates. The club has more than 300,000 contributors, 45 full-time or part-time employees and its own sophisticated computer.

In addition, Sen. Helms' top staffers have created four foudnations including the IAR -- an organization that does research and publishes studies on foreign affairs. Other foundations back "pro-family" positions and a return to the gold standard. All but one are tax-exempt. They provide information for the senator and his staff and pick up the tabl for their foreign travels. Last year these foundations raised more than $2 million; no other office on Capitol Hill has anything comparable.

This poltical conglomerate is widely suspected of being a Helms machine for a run at the White House some day. The senator dismisses that suggestion. "Cross my heart and hope to die, I've got no idea, no interest and no plan for running for president," he says.

Jesse Helms is a longtime Ronald Reagan supporter. Yet it's clear the Helms forces view the Reagan presidency as only a transition to what they see as real conservatism. Asked whether he agrees with his aides' assertion that conservatives aren't in charge in the Reagan administration, Sen. Helms says, "There is some evidence that pragmatism is being given more emphasis than it should be." including Defense Secretary Caspar Weinberger; no GOP senator has voted against more.

Both Helms lieutenants and conservative activists suggest that if Ronald Reagan does not run in 1984, when he will be 73 years old, Jesse Helms might. "Without Reagan, the top two contenders would be George Bush and Jesse Helms," says Richard Viguerie, the New Right direct-mail expert who works closely with the Helms empire. The senator, he says, easily could raise a record $20 million for the primaries and put together "a powerful, powerful coalition -- the lion's share of the pro-life groups, all the New Right and the religious right."

As he has moved from the status of fringe figure to national power -- leading fights against food stamps, abortion and school busing and defending right-wing regimes around the world -- the senator stirs as many passions as anyone in American politics.

"If there were an indispensable man," says Howard Phillips, the head of the Conservative Caucus, "Jesse Helms would qualify for the title without any close competion."

But to Senate Democratic Whip Alan Cranston, Jesse Helms "has introduced more meanness than I've seen in the Senate before." The Californian suggests Helms may be the "most dangerous" figure in the Senate since the late Joseph McCarthy.

It isn't just the liberals who are complaining. "I don't like the central issues, such as abortion, that Jesse Helms and his Moral Majority followers are pushing," says Sen. Barry Goldwater, the godfather of modern American conservatism. He says Sen. Helms isn't a "real conservative" in the Goldwater tradition and warns: "If Jesse and his followers continue to operate this way, we're going to see conservatism right back in the same fix we were in when I ran for president."

Many senators, liberal and conservative, complain Helms doesn't play by the rules. They say he introduces extraneous amendments and then uses the ensuing votes in election campaigns against Senate colleagues he wants to defeat.

The critics also point to the way he ran roughshod over Sen. Charles Percy, the chairman of the Senate Foreign Relations Committee, in holding up some of Reagan's State Department appointments. They say he brushed aside Senate Majority Leader Howard Baker's plan to postpone consideration of divisive social issues until the president's economic plan is enacted, after first privately promising to abide by that timetable.

Maybe, some think, Sen. Helms is getting too big for his britches. Perhaps a backlash is developing. Sen. Helms, his critics point out, could muster only six colleagues to vote with him against Chester Crocker as assistant secretary of state for African affairs and three colleagues to vote with him against Myer Rashish as undersecretary of state for economic affairs. Now he seems to be backing away from leading a challenge against Judge Sandra O'Connor, President Reagan's nominee for the Supreme Court, after being upbraided by Sen. Goldwater and others.

Still, Sen. Helms dismisses the sniping. For one thing, he explains, he is merely following the principles he believes in. For another, he says his opponents are simply "upset because finally conservatives are winning. As long as we were getting clobbered, I was just a courtly nuisance. Now that we're winning, I'm mean."

But Jesse Helms has always been tough.

The first campaign he participated in -- 31 years ago -- was the meanest in North Carolina's history. It pitted Frank Graham, the president of the University of North Carolina, against Willis Smith, the chairman of Duke University's trustees. In the final hours of the campaign, the state was flooded with pamphlets suggesting Graham was pro-Negro. The headline said, "White People Wake Up."

Helms claims he didn't play a major part in the Smith campaign, but others insist he was chief architect of Smith's strategy. In any case, Smith won and brought Helms to Washington as his administrative assistant. Helms subsequently returned to North Carolina to be executive director of the state bankers' association and then, for 12 years, to be the conservative editorial voice of Raleigh TV station WRAL.

He ran for the Senate in 1972, the year the Democrats nominated George McGovern for president. Helms won by opposing busing to achieve racial balance in the schools and by plastering the state with billboards linking his opponent to McGovern.

That compaign led to the founding of the Congressional Club. After the campaign, says Tom Ellis, who had been the campaign manager and who is now director of the club, "we were about $150,000 in debt. So we organized the club to pay off the debt. And we been plowing along ever since."

The club's big year was 1978, when Sen. Helms was running for reelection against Democrat John Ingram. That year, the club went "prospecting" across the country for contributors -- and found more than 300,000 of them. Helms raied $7.5 million and defeated Ingram, who spent $264,000, by 100,000 votes.

In 1980, its computer bulging with the names of contributors, the club went national. It contributed $65,000 to conservative candidates around the country, it paid for the senator's campaign swings, it laid out close to $4 million as an "independent expenditure" for Reagan's campaign and it ran three statewide campaigns of its own in North Carolina. It spent $8 million altogether.

Its biggest success was the election of John East, a little-known North Carolina college professor, to the Senate, upsetting the incumbent Democrat, Robert Morgan.

To manage East's campaign and the ultimately losing campaigns of Republican candidates for governor and lieutenant governor, the club, on the adivce of a prominent Washington law firm, reorgainzed itself as a corporation. That way, it avoided legal limites on the amount of money and services it could provide its candidates.

The club, camouflaged as a corporation, attacked Sen. Morgan's voting record in an effort to portray him as a liberal. Sen. Morgan, who had carefully built a moderately conservative image, was apoplectic, issuing a long, detailed "white paper" to rebut the allegations.

One of the charges leveled against the incumbent senator was that he voted to allow "union bosses" to use "forced dues" for political purposes. Actually, Sen. Morgan voted against a Helms amendment that would have barred unions, but not corporations, from using treasury funds to communicate with their members on political matters. The opposition also sought to link Sen. Morgan with Sen. Edward Kennedy and George McGovern as being weak on national defense, citing a vote against the B1 bomber. Actually, Sen. Morgan was a hardliner on defense issues and consistently supported the B1, except on one meaningless vote in which he was joined by most other Senate hawks.

The actualitites didn't matter. Morgan lost, East won -- and Jesse Helms became a man to reckon with.

The senator insists he shouldn't be given any credity; he says he knows little or nothing about the club, which really isn't his "personal possession." But Ellis, his friend and closet advisor, says the senator is the club's "titular head nad political saing." Helms photograph appears on almost every wall and on every desk in the club's headquarters, which occupies an entire floor in an office buliding in Raleigh.

This year, with the money still accumulating, the club has run a series of ads throughout the country supporting Reagan's economic program and mounted a campaign in North Carolina against Democratic Gov. James Hunt's proposal to raise the gasoline tax 3 cents a gallon to replenish the state highway fund. The ads attacked the program and, by implication, Gov. Hunt. Democrats don't think that's accidental, for politicans widely believe Hunt will challenge Helms for his Senate seat in 1984.

The club's ads attacked the governor's "cronies" for such alleged indiscretins as throwing their weight around to prevent state bulldozers from destroying two treasured magnolia trees. But the governor fought back with his own TV ads when money was needed for filling potholes. And the governor won; the gas tax was enacted. "We beat the hell out of them," exults Gary Pearce, Hunt's press secretary.

In Washington, some of the senator's aides weren't all that disappointed by the news from North Carolina. They see the club as a rival to their own activities, some of which are just as innovative.

That handsome town house on Constitution Avenue is the home of both the Institute of American Relations and the Foreign Affairs Council, each of which raised an estimated $800,000 last year. Other Helms operations include the Institute of Money and Inflation, run by economic aide Howard Segermark and wholly dedicated to putting the country back on the gold standard. And then there's the American Family Institute, which promotes conservative pro-family Institute, which promotes conservative pro-family positions and was run by Helms aide Carl Anderson until he landed a job at the Health and Human Services Department.

The Senator's aide among aides is 47-year-old Jim Lucier, described by Helms as a "brilliant young man, a deep thinker, a scholar." Lucier is active in the two foreign policy foundations.

Also active in these foundations -- and a founder of the Family Institute -- is the Peck's Bad Boy of the staff, fun-loving, roly-poly John Carbaugh, who can often be seen at expensive downtown restaurants whispering inside stuff to reporters. The senator says he has cautioned the 35-year-old Carbaugh against drinking champagne in the middle of the day and absenting himself too frequently from his "lovely wife and children." Carbaugh's hideaway is in the town house; he concedes the bottle of French wine on the stereo is his.

Lucier and Carbaugh travel abroad frequently, often to countries of South America and to South Africa. A serious flap occured on a trip to London in 1979 during the negotiations on the future of Rhodesia. British Foreign Minister Lord Carrington indignangly complained to then-Secretary of State Cyrus Vance that Lucier and Carbaugh were trying to sabotage the delicate negotiations. The two Helms aides deny it, but Carbaugh likes to recall a meeting they had then with the white Rhodesian leader, Ian Smith, who talked with them in his hotel room, in his bathrobe.

The third Foreign-policy expert on the senator's staff is Richard McCormack, who is not fun-loving. A rigidly disciplined man, he doesn't get along with Carbaugh at all He has told associates that Carbaugh tried to talk the Regan administration out of giving him a State Department Job. Carbaugh says he did no such thing.

The staff philosopher are Lucier and Segermark; both sometimes wander off conversationally into very deep waters. Lucier, for example, is developing a thesis involving "rationalist" and "normative" politicians. A rationalist, he says, is one who uses reason as the sole guide to his behavior, while a normative politician "never veers from the path of traditional Judeo-Christian values." Thomas Jefferson, he says, was a rationalist; his own particular hero, Patrick Henry, was normative. And Jesse Helms, even if he doesn't know it, is normative, too.

Segermark even while he works to take the country back to the gold standard, muses about "anarchical economics." That would be "an orderly society without government." Theoretically, he says, "you can make a case for it." The courts, he believes, could be operated by a private business.

Others on the staff aren't so solemn. During the campaign last year, about a dozen Helms aides paid their way into an Edward Kennedy fund-raising fete to listen to the music. Featured, they say, were black groups playing "beach" music. CAPTION: Picture, Sen. Jessee Helms with aides Jim Lucier and John Carbaugh . By Margaret Thomas -- The Washington Post