In the political snake pit known as Capitol Hill, Rep. James McC. Clarke is one of the gentlemen. The white-haired freshman Democrat, a North Carolina farmer and son of a Presbyterian minister, is known for his mild-mannered demeanor.

But what's this? A news release from the Washington-based National Republican Congressional Committee (NRCC) that says, "Congressman Clarke . . . evidently feels that we need to do nothing to prevent our older Americans from being beaten and raped on the streets of our nation."

Jamie Clarke, ambling through the corridors of the Capitol in a pale blue seersucker suit, simply shakes his head and says, "It's a sorry way to do business."

The business is a high-powered negative publicity campaign initiated by the NRCC, which organizes and funds GOP House races, against 70 to 100 incumbent Democrats. Republican and Democratic political committees have mounted such campaigns before, but never has the war begun so early and so stridently, more than 18 months before the elections.

The May 11 news release on Clarke, on red-white-and-blue NRCC letterhead, was sent to newspapers and radio stations in his district, as well as to several hundred of his major contributors. It attacks his vote against an amendment to a justice assistance act to increase the percentage of crime-protection funds devoted to the elderly.

Clarke acknowledges that his vote was "politically hasty." He said it was the result of confusion over the explanation of the amendment given him by Judiciary Committee Chairman Peter W. Rodino Jr. (D-N.J.).

Rep. Stan Lundine, a New York Democrat, was upbraided in an NRCC release March 9 for voting against an amendment to the jobs bill to provide $135 million for school and hospital weatherization. The release asks, "How could any member of Congress vote to deny money to keep hospital patients and school children warm in winter?"

Lundine, a fourth-termer from Jamestown, said five or six NRCC releases have been sent to news outlets and contributors in his district.

"This idea of sending it to your contributors--it's very close to being dirty tricks," he said.

News-release attacks were first organized into a sophisticated centralized operation by the NRCC in 1975.

It was called "News From the Other Side," but the Republican committee abandoned the tactic during the last election cycle as ineffective. The Democratic Congressional Campaign Committee (DCCC), however, began sending out negative releases in 1981, making political hay on GOP budget and Social Security votes.

Now the Republicans have started up again, with the new twist of sending the releases to campaign contributors. The NRCC has sent out more than 7,000 releases since February. It is also running paid newspaper and radio ads attacking incumbents in their districts for voting "wrong" on various issues.

Rep. Tony Coelho (D-Calif.), chairman of the DCCC, attacked the GOP campaign as "lies and below-the-belt tactics." He said the efforts "didn't work in 1982 and won't be effective in 1983 or 1984 either."

However, Joseph R. Gaylord, executive director of the NRCC, said, "We're just using some of the weapons the Democrats used on Social Security. They found it pretty easy to take cheap shots, so we can take cheap shots, too. And we have more guns."

The NRCC budget for this year is $26 million, Gaylord said, raised mostly through a sophisticated direct-mail operation with 1.2 million contributors.

It already is into candidate recruitment for the 1984 House races, and has begun training workshops. Gaylord said direct cash contributions to GOP races will amount to $8 million and that GOP candidates will have access to "state-of-the-art" video equipment to make television commercials, as well as a new computer service providing daily information on incumbent Democrats' votes.

By contrast, the DCCC, which began late in the direct-mail business, expects to spend only $8 million to $10 million for the two-year election cycle, and is still formulating a political game plan. Nonetheless, Coelho predicts that the Democrats, who gained 26 House seats in 1982, will add five to eight seats in 1984.

Gaylord said his negative media campaign is "a good tactic. It helps motivate people at the local level."

Besides press releases on individual votes, 20 Democrats were targeted as "the taxing 20" for voting in favor of the House Democratic budget, which, like the budget favored by Senate Republicans, included tax increases that President Reagan opposes.

The news release sent to Clarke's district--identical to those mailed to the 19 other districts--charged that Clarke "is forcing his average constituent to cough up $3,550 over the next five years while making it possible for him to receive an increase in his congressional pay of $2,792 in just the first year."

There were similar radio ads. However, in Clarke's case, WWNC, the largest station in Asheville, N.C., refused to air the ad on the ground that it was "distasteful."

That prompted an NRCC release blasting the station. "The only thing 'distasteful' about the ad is the decision of WWNC to become an editorial censor," it said.

Several members fought back, demanding equal air time to point out that the budget included no congressional pay raise, but allowed for an across-the-board raise for federal workers.

In one counter radio ad, Rep. Les AuCoin (D-Ore.) said, "I'm not intimidated by these lie and smear tactics . . . . If you're troubled by this kind of campaign, contact my Portland office . . . . "

Freshman Rep. Ronald Coleman (D-Tex.) got some favorable publicity from the experience. An editorial in his home-town paper, the El Paso Herald-Post, said Coleman was "rightly incensed" adding that the congressman "emphasizes that his concern is to do something about a whopping deficit that poses serious threats to the economy."

Over Memorial Day weekend, another wave of releases went out from NRCC headquarters to about 20 Democrats' districts, coupled with paid newspaper and radio ads charging that the Democrats proposed capping interest on mortgage payments at $10,000.

In fact, the cap was merely listed as one of many revenue-raising options in a report issued by the Democratic Study Group, an in-house information service subscribed to by 220 House Democrats.

"How could anyone in their right minds even think about capping home mortgage deductions?" the release asked. "Families depend on that deduction when they buy a home."

The paid ads, which ran in such papers as the Asheville Times and Newsday, gave readers the name and telephone number of their congressman and advised them to call and "tell him to get his own House in order. And not to tamper with yours."