He voted awarding a gold medal to Nazi hunter Simon Wiesenthal, a vote he describes as an error clearly out of tune with his staunch support of Israel and his own bill to bar foreign aid to countries harboring German war criminals.

He antagonized an NAACP audience by asserting that blacks are "genetically superior . . . because Southern white blood flows in every black today." When asked to explain his remarks at other forums, he recited his pro-civil rights voting record.

He befuddled an antiabortion contingent who sought his views on federal funds for abortion by discussing the ever-compelling subject of houseflies in India.

He has earned the wrath and ridicule of the political and corporate establishment with his unyielding opposition to dumping the dredging spoils of Baltimore harbor on two nearby islands -- effectively blocking deepening of the channel for a decade. He has feuded with his own congressional delegation, avoided facing reporters, and had his legislative ability called into question by members of his own political party.

In the world of political scuttlebutt, the word is out: Clarence Dickinson Long, Baltimore County's irascible nine-term congressman, is at the age of 71, slipping. Year by year, "Doc" Long's public utterances have caused more heads to shake in puzzlement and more of his old friends and colleagues to wonder whether the former college professor should retire after serving his district for 18 years.

The conventional political wisdom goes on to say that Long will win a tenth term in spite of himself.

He will also win, if this prediction is correct, despite what is being billed as the most credible challenge to his incumbency in Long's congressional career. Helen Delich Bentley, the former head of the federal Maritime Administration and longtime maritime editor of the Baltimore Sun, is running hard to unseat the venerable Long with considerable support from port interests and extra financial and technical aid from the national Republican Party.

"If Bentley can create a reason for an alternative and present herself as the viable alternative, it may be winnable," said Dick Minard, field representative for the Republican National Committee, which has targeted the contest as one of two Maryland congressional campaigns where Democratic incumbents are considered beatable. In the other race, Republican Newton Steers is seeking to regain his old Montgomery County seat from freshman Democrat Michael Barnes.

A three-month poll conducted for the Bentley campaign holds out some hope for the challenger: 30 percent of those surveyed said it was time for a change and 44 percent recognized the name of Long's opponent. The same survey also pinpointed a problem that may be insurmountable.

"Without a doubt, Long's strong suit is constituent service," said Minard.

"It comes out in everything we take a look at."

Clarence Long is, in fact, a phenomenon. His constituents seem to suffer his gaffes gladly in return for Long's constant and unending battles with the bureaucracy on their behalf. His office campaign headquarters may be a shared windowless room above a singles bar in downtown Towson but the real nerve center of his campaign is the district office a block away where serene caseworkers toil in the field of government red tape.

Bentley, the self-styled "Fighting Lady" whose campaign symbol is the World War II aircraft carrier bearing that nickname, strives valiantly to address what she regards as the issues. In particular, she pushes the port and argues that Long's opposition to dumping dredging spoils on Hart and Miller Islands will cost his constituents jobs as other cities dig deeper channels to accommodate the larger ships of the future. o

But to many constituents, even those who disagree with Long on the dredging, the issue pales. On what matters most to these voters, they will tell you, Clarence Long delivers.

"I'm quite concerned about Long's opposition," said George Gingher, 43, supervisor of technology for Bethlehem Steel, in a Dundalk cocktail lounge the other night. "But I don't know of anyone who does more to maintain contact with his constituents than Congressman Long. I don't know of any-one-myself or my neighbors-who would vote against him because of this."

Gingher is himself an example of Long's reach into the community. Interviewed at random, Ginghen said he had studied under the one-time economics teacher at Johns Hopkins University, and five years ago, as president of a local civic group, had found his old mentor most helpful in showing some student essay winners around the Capitol.

Long's network of personal contacts, built up over the years, follows his opponent as she trudges doggedly door-to-door through the Democratic streets she must win in order to prevail in a district where only 17.7 percent of the voters are registered Republicans.

In one such neighborhood last week, Bentley received a polite if unenthusiastic reception from most of the voters she approached. The dour-faced challenger, who has five dogs of her own and several pieces of dog statuary gracing her Luterville home, seemed also to greet the voters' dogs with somewhat more animation than she did their owners.

"Hi, there, pretty baby," she said, turning the meanest mongrel to mush.

To the voters, she introduced herself and handed brochures. A young aide armed with a computerized voter list followed close behind her, marking "receptive" next to the names of those who seemed to be.

But one such voter, the wife of a retired auto worker, told a reporter, "We pretty much stick to Mr. Long." He had helped their daughter on a personal matter, she explained.

"He's a proven quality and good for our area," said Mike Malinowski, a Bethlehem Steel welder who was working in his front yard when approached by Bentley. "A lot of gentlemen I work with feel the same way, basically."

The reception accorded Bentley was predictably warmer the day before at a coffee held in rock-ribbed Republican Riderwood, north of the city. Seventeen prim and proper ladies of leisure listened intently to Bentley's battle plan for victory.

"The mood of the country is for change," she asserted. "Congressman Long's been in office to long. He's never had any real opposition before. They didn't have the name identification."

Afer the spiel was over, Shirley McHenry, a Republican who has voted for Long in the past, said, "I've been waiting for them to come up with somebody against him for a long time. He's like a pro football player. He should get out when he's on top.

To say that Long is running scared wuld be to vastly overstate the case. He is, however, buying television ads for the first time in years, stressing his "issue" of constituent service, just as Bentley's media campaign highlights her major message on the port.

Long is also, despite disclaimers by his staff that he is too busy being a congressman to campaign, attending many meetings that serve a political purpose. They are not, by design, media events.

"Newspapers and I don't get along very well," said the congressman, cornered at one such gathering the other night after his press aide had repeatedly said Long was too busy to meet with reporters until Congress adjourns next month.

"If I were his aide -- talk about keeping Reagan from the press -- I wouldn't let him get within 4,000 miles of a reporter," said Peter Smith, a member of the New Democratic Coalition, an independent-minded Northwest Baltimore group that endorsed Long with several abstentions.

Smith recalled Long's recent appearance before his group. In response to his question about Long's racial remarks to the county NAACP, Smith said, Long "launched into a six-minute ramble. It was embarassing. Very, very sad. He's like a caricature of a congressman."

On the other hand, Smith said he found Bentley, who also appeared before the group, to be "a kind of hardhearted Hannah." "It's like Carter-Reagan," he said. "You feel a terrible dissatisfaction voting for either."

There was little evident dissatisfaction with Long, however, at the Ateaze Senior Center in Dundalk Wednesday night. Long's unexpected appearance caused a visible stir among the audience of 150 oldsters.

Bentley went first. It was, she knew, enemy territory. "He's bad for the economy and his voting record is hurting you and me," she asserted. Her stridency on the port issue was not well received, however. Long, who likes to portray himself in populist terms, turned the issue to his advantage.

It is only the rich Republicans of "the Valley," the country's WASPish enclave, who want to dump the dredged spoil on the pristine paradise of Hart and Miller islands, the congressman claimed. The chemically contaiminated muck, Long alleged, would seep through the proposed man-made island dike into the waters where generations of working men have fished and crabbed. Under this plan, he suggested, the deepened channel would inflate industrial land values at the expense of the people. "It's a scheme to make landowners rich," he said. He would dry out the spoil, using it for landfill to expand he harbor's rim, creating new public land for port expansion.

"I am up against the whole power structure, even the newspapers," he said, "but I feel it's the right thing to do."

His audience loved it, but they loved it even more when he declared defiantly, "I'm a senior citizen. I'm one of you. I'm proud of it."