REP. CLAUDE PEPPER, at 85 the oldest member of Congress, is late. It's only 6:40 a.m., but the Florida Democrat is behind schedule as he rushes into a waiting CBS-TV network limousine.

"They want to talk about abuse of the elderly," says Rochelle Jones, Pepper's press aide. He waves her silent and attaches two hearing aids. Jones begins again: "One question they will ask you is, 'Who is the typical victim? . . . '

"I know . . . ," says Pepper.

"Another question is: 'Are there any parallels between the person who abuses the elderly and . . . '

"Any what?" Pepper interrupts.

"PARALLELS," Jones repeats, leaning close to Pepper's left ear. "ANY PARALLELS BETWEEN EL AND CHILD ABUSE?"

" . . . I've forgotten, but I think there is more elderly abuse than child abuse, or was it the other way around?"

"NO," says Jones loudly, "THERE IS MORE EL ABUSE . . . IT'S INCREASED SINCE YOU HELD HEARINGS IN 1981 BY 4 PERCENT PER YEAR OR ABOUT 100,000 CASES."

"In child abuse?"

"NO, ELDERLY ABUSE."

"Yes, when did we start?"

"YOU HELD THE FIRST HEARINGS IN 1981."

"1981?"

"1981. THAT'S CORRECT . . . "

The CBS television studio on M Street is confusing. Correspondent Bob Schieffer, who is in a New York studio, will interview Pepper during the "CBS Morning News." Schieffer's face will appear on a large television screen at Pepper's right. But Schieffer's voice will come from a floor speaker near Pepper's left foot. Pepper, meanwhile, is told ook neither left nor right, but straight ahead into a camera.

"Rochelle?" calls Pepper, as the "CBS Morning News" title appears on screen.

"YES SIR?"

"The hearings, were they before our full committee?" "YES, SIR."

"And they were in . . . "

"IN 1981,SIR."

"1981, okay, okay. 1981." MORE THAN ANYONE ELSE, Claude Denson Pepper is seen as the spokesman for the 26 million Americans age 65 or older.

A Time magazine cover of Pepper in 1983 called him "Champion of the Elderly." He is known on Capitol Hill as "Mr. Social Security" because of his dogged fights to spare it from cuts. He remains the most sought-after campaign speaker in the Democratic Party because he can draw huge crowds of the aged, the fastest growing segment of society, the one with the best voting record.

"Claude Pepper has come to symbolize the elderly in this country," says Jack Ossofsky, executive director of the National Council on the Aging.

Pepper's enthusiasm is inspiring. Although he is paunchy, hard of hearing, slightly stooped and has a mechanical valve in his heart that beats with the help of a pacemaker, Pepper regularly works 15 hours -- or more -- a day, chairs the powerful House Rules Committee and travels frequently, carrying his own bags, thank you.

When he had his pacemaker surgically inserted three years ago, he is said to have asked: "How long will the battery in this thing last?"

"About 10 years," the doctor replied.

"Then you'd better give me three of them now," Pepper said. "I'll come back later for more if I need them."

"AN OLDER WOMAN once told me that you can foresee old age, but you can't fore-feel it," says Ossofsky. "Claude not only sees the issues, he is aware and feels them. He has an insight that you only get when you are there . . . "

As with any pson his age, being there shows. Pepper often takes afternoon naps, forgets names and retells the same stories. Sometimes he asks his staff to drive him from his congressional office across the street to the House for a vote because he is too tired to walk.

Pepper denies that he has lost any physical or mental ground, and he resents the senility microscope placed on him. He at first takes on a witty composure to charges that he may be slipping. "I've had to slow down a bit," he says, smiling. "Some Sundays when it is hot and I'm playing golf, I get tired at about the 16th hole and it takes me a bit longer than normal to shoot all 18."

Pushed, he becomes irritated, complaining that reporters do not ask such questions of other congressmen. All Pepper has to do is accidentally push the elevator's up button when he wishes to go down and there are whispers.

"I do my best," he says. "I try to put in a full day." He rises early, works late and has taken on a full agenda. Besides protecting Social Security, there are immediate concerns within his own district: Radio Marti, which broadcasts U.S. propaganda to Cuba, needs $3 million and Florida bankers want him to keep a branch-banking bill bottled up. His 1986 reelection campaign needs money. There is an autobiography to finish.

"So much to do," he says. "So much to do. I'm just too busy to get any older," he quips. Later that evening he becomes more introspective. He talks of his wife, Mildred, who died of cancer in 1979 after 42 years of marriage. Her death rocked him: "I never think of myself as an old man. It shocks me in a way to think that I am. But I am actually an old man! I don't believe it. I don't believe it. It happens so gradually . . . No one wants to go unless you are in some terrible, terrible pain. You just don't want to go." The real difference between himself and his colleagues, he says quietly, is "they have more time . . . "

PEPPER GREW UP poor in rural Alabama, the oldest of four children.

"I remember earning 65 cents per day as a youngster doing plowing," Pepper recalls. "On the way home I stopped at the drugstore and bought a grape juice drink. It cost me 10 cents and, my, it was so delicious, cold and sweet. I remember thinking that I hoped I could see the day when I could finish one of those grape drinks and say, 'Give me another.'

He has always worked. He paid his own room and board at the University of Alabama by hauling coal and ashes every day at a power plant and later waited tables to help finance his legal education at Harvard.

"I shudder to think what I would have become if I hadn't been able to get a good education," says Pepper.

After graduation Pepper taught briefly and then settled in Florida where he developed a reputation for defending the poor and uneducated. In one case, he kept the state from executing one of his clients for 19 years until prosecutors gave up. Pepper's client died in jail, of old age.

Pepper was elected to the state legislature in 1928, but was voted out of office after one term after he refused to support a resolution that censured Lou Hoover, the wife of Herbert Hoover, for inviting a black person to a White House tea. Pepper left rural Florida after that for Tallahassee and took his parents with him. He cared for both of them until they died.

Eight years later, Pepper was elected to fill a vacant Senate seat. He immediately fell under President Franklin Delano Roosevelt's spell.

Pepper's loyalty to FDR prompted the New York Herald Tribune to write "when the White House has an important balloon to send up, it invites Senator Pepper to supply the necessary oratorical helium for the ascension."

That loyalty to FDR helped end Pepper's Senate career. In 1944, Roosevelt asked Pepper to support the veto of a tax bill favored by Edward Ball, the politically powerful businessman who controlled the multimillion- dollar DuPont estate in Florida. Pepper agreed and Ball vowed revenge.

Pepper soon made another powerful enemy by joining a movement at the 1948 Democratic convention to dump Harry S Truman. Time magazine reported that Truman summoned then Congressman George Smathers to the White House and said: "I want you to beat that son-of- a-bitch Claude Pepper."

Smathers challenged Pepper in 1950, waging a campaign that is described by Robert Sherrill in his book, Gothic Politics in the Deep South, as the "most elaborate crusade of political annihilation ever conducted in southern politics."

Pepper was mercilessly attacked for his antisegregation views and openness toward the Soviet Union, branded at one point as "Red Pepper."

He was soundly defeated and returned home broke. In the next eight years, he built a profitable law firm in Miami. He lost a Senate bid in 1958 but was elected in 1962 to a newly created House seat in Dade County where the population had doubled in a single decade and 80 percent of the registered voters were Democrats.

Pepper was, at first, a politician without a cause. But in the mid-'60s, when Miami's crime rate became the highest of any large city, Pepper hustled a bill through Congress that created a joint House-Senate committee on crime. He became its chairman. The committee was criticized as being a publicity stump for Pepper and was abolished in 1974.

In 1977, Pepper was named chairman of the House Select Committee on Aging and he quickly gave it national prominence by using many of the same publicity gimmicks that earlier had incurred his peers' contempt.

This time, though, Pepper had a track record: a concern about the elderly that can be traced back to his state legislature days when he penned a law that allowed persons age 65 and older to fish without state licenses.

Protecting Social Security from budget cuts soon became his chief goal. In 1982, Pepper campaigned for 70 Democratic candidates in 25 states and at each stop blistered President Reagan for proposing cuts in benefits.

"I would grab the hand of the Democrat that I was helping, and I would raise it high and I would say, 'And this man or woman promises you that he or she will vote against cutting Social Security.'

Nevertheless, when the Social Security package reached the House floor in March 1983, Pepper lost. His colleagues gave him a standing ovation after his speech and then overwhelmingly rejected his proposal.

"I know who they are," Pepper says of the Democrats whom he helped elect and who later voted against him. "And when there has been an opportunity for me to do something for them, I haven't done it." Recently, Pepper has been quietly voting more conservatively because his district now has more Cuban Amer- anywhere else in America. Most are not liberal.

"Rep. Pepper has grown more conservative," says Richard A. Pettigrew, chairman of the Dade County Democratic Executive Committee, "but he has remained essentially true to his fundamental vision of this country -- that everyone, no matter how lowly their beginnings, deserves an opportunity."

And as Pettigrew sees it, the congressman has satisfied his constituency: "Quite frankly, Pepper could be re-elected here posthumously."

WGBS RADIO talk show host David Gold was blunt during a recent on-air broadcast in Miami: "Do you think that Claude is playing with both oars in the water?"

It's a question, says Tom Fiedler, the Miami Herald's political editor, being asked in local political circles.

"It's clear that Pepper gropes a lot of the time to orient himself to what he is doing," Fiedler said. "I think he is slowing down mentally."

Radio host Gold, who has had Pepper as a guest on his show, is harsher: "No one wants to talk about it because he is such an endearing man, but I think Pepper, at times, is incoherent, especially if you get him off subjects that he knows by rote like Social Security. His staff protects him and drags him around by the nose."

Pepper's image in Washington is different. "He is simply brilliant," says Christopher J. Matthews, administrative assistant to House Speaker Thomas (Tip) P. O'Neill Jr. (D-Mass.).

"I have been simply dumbstruck by Representative Pepper's ability to recall details about his discussions with President Roosevelt, talk about complicated budget matters and then weave them together lucidly to make a point," says Dr. Robert Butler, founding director of the National Institute on Aging at the National Institutes of Health.

Adds Rep. David E. Bonior (D- Mich.), a member of the House Rules Committee: "I've never known Pepper to have had any trouble following any issues."

Several other House members, who would not allow their names to engages in political demagogy and is more comfortable with generalities than substance. Not one, however, questioned his mental abilities.

Pepper's severe hearing loss could explain much of the criticism levied by Gold, who complained that Pepper kept asking him his name during breaks on his radio show.

The aging council's Ossofsky recalls a press conference during which Pepper seemed confused until a reporter repeated his question. "Then Pepper effectively galvanized the room by answering it better than anyone else on the panel."

The most often quoted incident of Pepper seeming to be confused occurred in June 1984 during a fierce House battle over the MX missile. So crucial was the vote that the Reagan administration hched Air Force jets to ferry back out-of-town congressmen who might vote for the missiles. In the House itself, Speaker O'Neill, cigar in hand, hovered, counting votes, pressuring party members who wavered. In the end, MX opponents won the skirmish in three votes: 199 to 197, 198 to 197 and 199 to 196.

Pepper, who eventually supported building the MX, did not vote.

The next day, the media speculated that Pepper had avoided the vote as a favor to O'Neill. But Pepper denies that. "The speaker," Pepper said, "came over and he said, 'If I were a man your age, I'd go home and go to bed.' He said there probably wouldn't be any more votes and if there were any, they would be late at night. I thought about it awhile, and then I went home and went to bed."

O'Neill's press aide declined to comment on Pep- per's explanation, but congressional aides and reporters found it damaging. "Either O'Neill hoodwinked him, which is his fault, or he simply didn't know what was going on," said a Hill aide. whetherthe House should cut $3 million from the budget of Radio Marti, Pepper rose and without notes and little preparation delivered a speech so eloquent that his colleagues stopped talking among themselves and later applauded loudly.

"Let us not silence, let us not soften the voice of liberty and freedom and democracy," Pepper said. "Let us put wherever we can the arm of words, as we did in other days of this country with our Declaration of Independence, ideas more powerful than guns."

"Claude Pepper is bound to have slipped some with age," says Pettigrew. "But I'd rather have Claude Pepper at 75 percent than most politicians at 110 percent."

CLAUDE PEPPER holds a photograph of his wife in his hands as he sits in his apartment dining room. "Many people thought she was the most beautiful woman in Washington when we first came here. She was so intelligent and so witty."

He looks around. "Everything is exactly the same here as t was when Mrs. Pepper left it," he says. "I feel a considerable closeness to her here. I didn't want to disturb the place that I'd been with her.

"Her toilet articles are all in our bathroom and on the shower curtain there is a little note: 'When you are finished your bath, please close the curtain.' Apparently, I had been leaving the curtain open so Mrs. Pepper left me this note. It's still up there."

He recalls the first time he saw her. "She was wearing a bright yellow dress and when I saw her, I said, 'That's the prettiest girl I have ever seen. I've got to meet her.' "

Five years later, they were married. She was sick with the flu at the time. "I always used to joke that she prob- ably wouldn't have said 'yes' if I hadn't caught her at a weak moment," Pepper jokes.

"They were just a delightful couple," says comedian Bob Hope, a family friend. "Mildred had a delightful sense of humor . . . I know when she left."

The Peppers spoke only once about the possibility of Mildred dying after doctors diagnosed her cancer.

"We were having breakfast one morning in Miami. She was sitting across the table from me and suddenly, she said with considerable sadness in her face, 'Claude, I guess we have just about come to the end of the road.'

"Well, I burst into tears and rushed around and embraced her, and I said, 'Don't say that. I can't live without you!' And she never said a word again about it.

"I realized later that one of the greatest tragedies of my life was that I never told her, we never talked about, how much, I, uh, but you see I never abandoned hope. I always thought that they would find some cure, and I never wanted her to get down, so I just never talked to her about her, uh, going. I later found out that she had known her condition all along. I hadn't hidden anything from her. I'd only missed the chance to say goodbye.

"That has caused me much sadness, much sadness."

Pepper later spoke adamantly in Congress in favor of a bill that would have allowed patients suffering terminal illnesses such as cancer to use heroin.

"I told them about my wife's suffering . . . about that killing, terrible pain, but they were afraid that they'd be accused of voting for drugs, the bunch of damn weak, spineless bastards."

He was at her side when she went into a coma and he was still there days later when she died.

"At night," says Pepper, "when I go into our bedroom and look at her bed next to mine, I say, 'Hello darling, hey' and I sit down and think of her and talk to her and that helps, but I still get very lonely for her, very lonely."

"I think my brother would be dead in six months if he ever retired," says Frank Pepper. "After Mildred died, his job became his life."

CLAUDE PEPPER is having trouble eating. A stream of admirers interrupt him at the Columbia Country Club.

"You are one of this country's greatest Americans," says one white-haired man.

"God bless you, Claude Pepper," says another.

"My, my," says Pepper, "people say the nicest things to me."

"I have always considered politics a form of ministry," he says. "It has an almost religious feeling to it. That's why I can't understand this man Reagan.

"I hope I will be around in a few years when the spell of his personality wears off and serious-minded politicians sit down and try to evaluate him. Is he a clown, a barker at a circus? Who is this man? This Ronald Reagan?"

He is asked: "What will historians say when Claude Pepper is gone?"

He is genuinely startled at the thought. Claude Pepper does not consider death, and he has no immediate answer.

INSIDE THE CBS studio, Pepper sits slumped in a chair on the small stage set, the floor speaker by his foot, the screen to his right, the camera dead ahead. He stares straight forward. He is tired. Earlier, he had complained: "I don't know how many more of these I want to do. It's too hard getting up at 5:30." He looks very old.

"Okay sir, five seconds," the cameraman says, and begins the countdown on the fingers of his outstretched hand. As the seconds tick off, Claude Pepper begins a remarkable transformation. He shifts his body forward, he looks suddenly alert, his right hand moves upward, ready to stab the air to make a point. Hang on, America, curtain coming up.

When Schieffer asks how serious a problem abuse of the elderly is, Pepper is center stage, his voice loud and commanding.

"It's extremely serious, Mr. Schieffer, and it is growing more serious all the time. Our committee on aging held its first hearing on this subject in 1981 and we were SHOCKED to find out the extent of this abuse. It has increased about 4 percent, about 100,000 cases per year since we held those hearings." The timing between words and phrases is perfect, the diction flaw

"Who are the victims, Congressman?" Schieffer asks. "And who are the people causing this abuse?"

"Most of the ABUSE comes from INTIMATE family members," says Pepper, accentuating key words, preparing now for the touching tale. "For example, we had a SHOCKING case where a son ROBBED his mother of her money and BEAT HER UP and RAPED her . . . "

"What should be done?" asked Schieffer.

Pepper doesn't flinch. His reactions are as polished as Sir Laurence Olivier launching into Richard the III's final soliloquy. The words tumble out effortlessly.

''We must set up organizations to encourage and put pressure on those who have knowledge about abuse of the elderly to report that abuse," says Pepper. "States must pass tougher laws to prevent elderly abuse and federal funds must be allocated to organizations that make preventing such abuse a priority." He ends, of course, with a warning directed to the audience: "Almost every case where an elderly person is confined is a prospective case of abuse . . . "

It has been another successful performance by the master politician. Claude Pepper, the poor southern boy who at 15 dreamed of being president of the United States, has been tested once again. He can still bring down the house.