The candidates are young, scrubbed, intense. Relentlessly, they hammer their message: The District of Columbia is becoming a "bacchanalian swamp" . . . a "snake's nest" . . . as warm with gamblers, homosexuals and "mindless potheads."

Moonies? No. Baptist ministers? No.

They are members of the U.S. Labor Party, a little-known but aggressive organization that is running five candidates in the Nov. 7 city elections to fight what they say are the plans of the Democratic candidates and their worldwide liberal "no-growth" manipulators to ruin the city and bring its population under drug-induced social control.

They have been bringing the same shrill message here since 1974, running candidates without success for various City Council and school board seats. Despite their dogged energy, they rarely have captured more than one or two percent of the vote, although one Labor Party candidate received almost 20 percent in last year's sparsely attended school board race, coming in third in a four-way contest for an at-large seat.

Party activists, who show up constantly at candidate forums and on television panels brimming with abrasive, apocalyptie rhetoric, have left their opponents puzzled and annoyed.

"I'm running," says Susan Pennington, Labor Party candidate for mayor, "because of the thousands and thousands of people who can't stomach Marion Barry."

If Barry and other liberal Democrats win on Nov. 7, says Bruce Director, Labor Party candidate for City Council chairman, "this city could come under a hideous form of social control not seen since the Roman Empire."

Democratic candidates for various city positions wince when asked by reportes about their Labor Party opponents. Barry has refused to appear in joint debates with Pennington. Other Democrats complain of being hectored and verbally abused by the party's candidates at public forums in this year's campaign.

Barry refuses to debate Pennington, says Barry press secretary Florence Tate, because "her attacks on him are patently false and irresponsible."

Pennington says Barry will not debate because "hes afraid."

A key tactic in the Labor Party campaign has been to seize upon concern among portions of the public increasingly permissive laws and court rulings on sex, gambling and drug use. Party activists say they are meeting with success.

Pennington, who has run unsuccessfully in four previous races in Washington since 1974, says the party already has made inroads into traditional Democratic strongholds, especially among conservative church-going blacks who voted for incumbent Mayor Walter E. Washington in last September's primary and are alarmed at Barry's more permissive view of gambling, gay rights and marijuana decriminalization.

Other Labor Party activists also say they are beginning to build a political base among such diverse sectors of the city as the Black Muslims and rank-and-file trade union workers.

Small but well organized, the Labor Party has mounted a campaign that has given it generally more visibility than the scattering of independents, Socialist Workers party and D.C. Statehood Party candidates in the November race. The Labor Party has moved from a seedy office at 7th and K Streets NW to a more expensive office building at Vermont Avenue and L Street NW and is pouring out an avalanche of well-designed political literature and candidate posters.

The Labor Party is not new. A spinoff of the old Students for a Democratic Society in New York, the 2,000 member national organization has undergone various political metamorphoses in the last 10 years, from radical Marxism to current advocacy of 19th century "Whig" industrial capitalism.

Party candidates have run for office in numerous states since at least 1974, and the party has an international apparatus that has entered candidates in races in West Germany, Italy, Sweden and Mexico.

Its various regional offices, including the one in Washington, are connected by an elaborate Telex communications system. Members estimate the party's weekly national operating budget at $40,000 to $50,000.

Disciplined and authoritarian in structure, the party is headed by Lyndon H. LaRouche Jr. from his New York headquarters. LaRouche, who ran for President on the labor force ticket in 1976 and received 40.035 votes, preaches a "pro-growth" economic policy of maximized industrailization and development of fusion - as distinct from fission - nuclear power.

Environmentalists, conservationists and other advocates of "austerity" programs, by contrast, the Labor Party says, simply are part of massive worldwide "Rockefeller-Carter-Tory-Atlanticist strategy" to do one of two things: destabilize society and trigger civil unrest by instigating labor strikes, terrorism, power blackouts and hijackings; or, deindustralize society and convert workers into passive drones through permissive use of marijuana and other drugs.

This is the message that the five Labor Party candidates in Washington bring when they are on the stump. Trash pickup, education, housing, police protection, street repairs - the bread-and-butter issues of D.C. voters - all have global implications under Labor Party analysis.

The five Labor Party candidates devote many hours to party work. Most hold part-time jobs and live sparingly on savings and limited income.

Pennington, 35, describes herself as a part-time legislative specialist for a national women's organization. She would not name the organization.

Director, 25, who is running for City Council chairman, works as a teller in a local bank.

The other three Labor Party candidates are:

Cloid J. Green, 28, who works in a small hotel and drives a taxi part-time. He is running for D.C. delegate in the House of Representatives.

Stuart Rosenblatt, 27, who works full-time as chairman of the local Labor Party. He is running for an at-large City Council seat.

Suzanne Klebe, 25, who operates a typesetting machine in a graphics shop. She is running for the Ward Council seat.

All are white, middle-class, well educated, aggressive and skillfully versed in Labor Party logic.

The group forms part of the central cadre of the Labor Party in Washington, which has an official totla of 53 registered members, according to the D.C. Board of Elections and Ethics.

Close mouthed about details, party members refuse to name sources or leaders in voter constituencies where they claim to be making inroads.

"We have a great deal of rank-and-file trade union support," says Rosenblatt, "and we have been in touch with the Nation of Islam (the Black Muslim organization now known as the World Community of Al Islam of the West)."

Khalil Abdel Alim, imam of the World Community mosque here, said in a telephone interview that he has had discussions initiated by Labor Party members about "the drug problem" but his organization as a policy matter, has not endorsed or supported the Labor Party or any other party.

"That's right," Rosenblatt agreed. "It's simply discussions at this point."