Rep. Roy P. Dyson (D-Md.), who represents the mostly rural 1st Congressional District, proudly announced his appointment to the House Agriculture Committee last year.

Less highly publicized was that the appointment was made largely to give a political boost to Dyson, one of the most vulnerable Democrats in the House because of a widespread perception that he has been too close to interest groups that have contributed to his campaigns over the years.

As a new Agriculture Committee member, Dyson has delivered for his sprawling Eastern Shore and southern Maryland district, backing a soybean marketing program, supporting higher payments for area farmers who set aside land near rivers and streams, and bringing committee Chairman Kika de la Garza (D-Tex.) to the district for hearings.

At the same time, Dyson has accepted nearly $26,000 in contributions from the agriculture industry, a figure almost certain to increase if he wins the Sept. 11 Democratic primary. He received $6,500 from cane and beet growers from as far away as Hawaii before he voted against cutting sugar price supports.

Dyson said his sole concern was maintaining a strong domestic sugar industry. "Do you want to look at the issue or do you want to deal with perception?" he responded when asked about his vote.

Programs like the sugar price supports are needed "to sustain agriculture, not just in Maryland but throughout the country . . . so that we have never . . . had to go through food shortages . . . . "

Even with Dyson's explanation of that vote and others in which his contributors have had a keen interest, he remains embattled as he seeks a sixth term. In the primary, Dyson faces state Del. Barbara Osborn Kreamer (Harford) and two other Democrats, while Republicans will choose a candidate for the Nov. 6 general election from among eight contenders.

It is a race that will test Dyson's reputation as a political survivor, a mark he earned after winning reelection amid controversy in 1988 and then aggressively trying to broaden his support even as state Democratic Party Chairman Nathan Landow was scouting for a replacement.

Last week the test got tougher after Dyson acknowledged being a conscientious objector during the Vietnam War, a fact that contrasted with his support on the House Armed Services Committee for military operations abroad and his acceptance, in this campaign alone, of more than $100,000 in contributions from defense-related political action committees. Dyson, indeed, has used his post on the committee as a centerpiece of his campaigns in a conservative district laden with defense installations and contractors.

To receive designation as a conscientious objector, an individual is required to swear in writing that he is "by reason of religious training and belief . . . opposed to participation in war in any form." Yet Dyson says he is no pacifist: He was opposed only to fighting in Vietnam and has always favored a strong military force.

Dyson said he is willing to use force today in the Middle East, Panama and elsewhere because the military services are all volunteer and such military actions have had popular support.

Selective service records indicate Dyson was awarded status as a conscientious objector in 1971, one month before his student deferment was due to expire. His number in the national lottery, 131, was within those eligible to be called for service.

People who served on the St. Mary's County draft board when Dyson's case was heard said they don't remember voting on it and expressed surprise at his status as a conscientious objector because that typically was reserved for members of pacifist religions. Dyson is Catholic.

Carl Laffler, president of the St. Mary's County Commission and a Republican friend of Dyson's, said the issue has hurt Dyson badly. "In St. Mary's a lot of the votes are military, and he's been preaching to us. People seem really devastated because when things are concealed . . . the momentum builds."

In an interview last week, Dyson described his feelings against the Vietnam War as "intense." According to his selective service records, he objected even to serving as a noncombatant in the medical corps.

The issue has generated a strong backlash from veterans in his district, callers to radio talk shows and his political opponents, who have used it to highlight what they view as inconsistencies in Dyson's record.

On the environment, for example, they criticize him for talking about the declining oyster harvest and the need to clean up Chesapeake Bay, while proposing legislation reducing protection of non-tidal wetlands, a stand that has won him important support from farmers and some landowners.

Dyson, however, points to other parts of his record: He has helped secure money, for example, to decontaminate a naval training campus in Cecil County so the land can be developed, and comments, "The environmentalists aren't always right." Current non-tidal wetland laws, he said, would shut down development on large parts of the Eastern Shore to protect land that is dry much of the year.

On other issues, the self-proclaimed fiscal conservative has been assailed for his use of Congress's free mailing privileges. And two weeks ago Kreamer took him to task for an ad that featured a homeless constituent; Dyson had voted against landmark homeless relief when it was first before Congress.

Campaign aides say that Dyson's record on housing and other anti-poverty legislation is strong, except for that one vote, and that the hundreds of thousands of pieces of mail he sent out at taxpayers' expense were his way of "keeping in touch."

Dyson, a native of tiny Great Mills in St. Mary's County, was first elected in 1980. He served four terms in relative obscurity, well funded and seemingly unbeatable, until 1988, when his longtime chief of staff, Thomas M. Pappas, committed suicide.

That suicide, the day a Washington Post article detailed Pappas's unorthodox management of Dyson's office, led to intense scrutiny of Dyson's House record and fund-raising. Pappas, it was disclosed, had received tens of thousands of dollars in consulting fees from Dyson's campaign and apparently had augmented that by having aides cash checks on the campaign treasury and return the money to him. The campaign was fined $3,000.

Dyson's name also surfaced, though not as a target, in a federal probe of defense contractors who had funneled thousands of dollars into congressional campaigns, including Dyson's. He was criticized also for voting in favor of a Pentagon truck contract on the day he accepted a $2,000 honorarium from the company.

The controversy took its toll and is still the fodder for opponents' ads. After spending $680,000, Dyson defeated political novice Wayne Gilchrest in 1988 by just 1,500 votes.

Dyson has run hard ever since, making frequent appearances throughout the district's 13 counties. Last fall he announced he was returning $19,000 to defense consultants and donating the $2,000 honorarium from the truck company to charity. He conceded mistakes in judgment.

Interviews and an analysis of Dyson's record indicate that he has been successful in furthering local projects. For example, he helped win extra federal money to study the Chesapeake Bay and conserve Ocean City's beaches.

Observers, however, say Dyson's involvement and influence do not extend far beyond such parochial efforts to bring more money and jobs into his district. Each year he introduces legislation setting the budget for the Panama Canal Commission, which falls under the House Armed Services subcommittee he chairs. Otherwise, his remarks in the Congressional Record tend to be limited to tributes to constituents, thanking colleagues for help with local projects or to advocating weapons that Maryland companies help build.

Dyson contends that frequently the national interest coincides with the local needs he pushes.

Consider the case of the F-14. When Congress, including Dyson, opposed efforts by Defense Secretary Richard B. Cheney to stop adding new planes to the U.S. fleet, local protectionism seemed to be overriding national spending priorities. Grumman Aerospace employs more than 500 people at its plant in Salisbury. (Dyson had helped recruit the company to an abandoned shirt factory.) And more than one-third of the work force could have been unemployed if Cheney's plan had succeeded.

Dyson said the current Mideast crisis shows Congress's position was correct.

"The F-14 may save our day," Dyson said. "The fact that the {electrical} harnessing is being done in Salisbury is not that relevant to all of it. There is a great national concern, and that is to protect our soldiers."

There is a flip side to the story, one that Dyson's challengers emphasize. Grumman, like many defense firms, has been a dependable source of campaign contributions to Dyson, giving the maximum $5,000 to his primary race this year.

Criticism about Dyson's ties to the national PAC pipeline hurt him in 1988. Nevertheless, he has raised more than $434,000 since January 1989, about $277,000 of it from political action committees.

Before last week's controversy over his draft status, Dyson appeared to retain a good degree of voter affection, chatting amiably as he knocked on doors in a predominantly black neighborhood in Salisbury or shaking hands on plant tours. His campaign has gathered endorsements from fellow Democratic officeholders, including the mayors of Salisbury and Aberdeen.

In interviews conducted in July, few residents in the district recalled the controversy of 1988, and fewer still said it turned them away from Dyson. Most said Dyson had represented the district's interests.