When they talk about their leader, Robert C. Byrd, Senate Democrats and others prominent in party affairs often opt for a two-track approach: first they talk on the record, then off.

On the record, they say the sort of things that Byrd would like to cut out and paste in his scrapbook or, better yet, reprint in his 1982 campaign brochure.

Off the record, or speaking with the assurance of anonymity, they say things of another sort, as in this conversation with one of Washington's leading Democrats:

"On the record," he began, "I had doubts right after the election about whether Bob Byrd could ever adjust to a minority role. After all, he'd never had a setback before. He started right at the bottom and went only up. But I think he's done a good job. He's clear spokesman for the party."

"Now, not for attribution," he went on, with barely a pause for breath, "truth is, nobody likes the sonofabitch. He's impossible to deal with . . . a man of tremendous insecurity. He's most difficult to be around. . . . He has no freinds. . . . He really isn't a leader, he was a housekeeper. . . . He's like the conductor on a train."

The truth is the Senate's Democrats don't feel much fondness for their leader and don't feel very comfortable around him. Talk with one Democrat about Byrd and you've pretty much talked with all of them. It is one subject on which they have achieved a remarkable degree of unity.

They talkabout how they believe Byrd went through a period of shock and even depression after the election that cost him his Senate contol, which was his very existence. They talk about how they believe he is, deep down, a very "insecure" man. The word is frequently volunteered by his colleagues.

They talk about how he does not have a single close friend in the Senate, where he has served for 22 years. About how he is vain and petty and jealous of the perquisites of power, out at the same time is scrupulously fair in his dealings with his colleagues. About how he is feared by his staff, with which he is said to be strict and even abusive.

And about how he is unsurpassed in the tactical skills of running the Senate floor, which is the job of a majority leader, but how he is unsuited for the very different role of the minority leader, which places greater emphasis on being a spokesman for substantive party positions and an out-front, on-camera leader of the pack.

But then, significantly, these Democrates go on to recite the central facts of life in the nation's capital. They concede that it is unlikely that any other senator could have done any better than Byrd has done in this time of down-and-out Democratic fortunes.

They concede that no one could have mended the compound fractures that seemingly have immobilized this Demoratic body politic that once so dominated the Senate. And most senators go on to say they doubt that anyone will mount a sucessful challenge to unseat Byrd as Democratic leader of the Senate.

But although he survives in office as the minority leader of the Senate, Byrd may be the one man in America who lost more than Jimmy Carter did last November.

"The Senate," Byred used to say, "is my life." It was also, for this man of dirt-poor origins and foster-home upbringing, his family, his roots and his identity.

Last year, Byrd, as leader of the majority, was in charge of running the Senate, and he did so with particular paternal pleasure. He made himself leader there not because had made his peers admire him, but because he made them feel they owed him.

He never took a vacation in 30 years and never played a round of golf, but was always on hand to do the Senate chores no one else wanted to do. He had no skills of grand oratory, no flair for substantive innovation, so he made himself, a master of parliamentary maneuver, And this proved to be his greatest skill as majority leader once he claimed the job by cashing his amassed fortune in chits.

On the floor, Byrd reveled in the parliamentary regality of it all, lecturing the Senate once a week on little-remembered moments of its history. Back home in West Virginia, he began laboriously signing each autograph, "Robert C. Byrd, Majority Leader, U.S. Senate."

This year, Byrd, as leader of the minority, is in charge of running nothing. His work is done now in the shadows that fall upon the minority, and his greatest skill, the running of the Senate floor, is about as useful this season as the art of blacksmithing. He forms task forces and calls meetings, in the hopes of forging a consensus, or at least providing a little illumination.

He has sought to steer his out-party colleagues toward at least an occasional place in the sun, but so far has basked mostly beneath clouds of disarray.

The minority leader of the Senate is doing nervous little around his office, tending to domestic chores as he speaks his way through a long monologue of an answer he has clearly thought through well in advance.

It seems designed to answer all of the whispered accusations and put to rest all of the lingering doubts. It is a stream of self-consciousness, one single answer divided into chapters: the Democrats as a minority, himself as their leader, his accomplishments to date, and how the Democrats are really not in disarray. It goes on for about 25 minutes.

"It really isn't so frustrating as one would imagine," Byrd says. He is the possessor of a rather small, rounding body that is always dapper in suit with vest, and which crests in an impressive blue-gray plumage that is combed back and up into something that is a cross between a pompadour and a ducktail. As he speaks, his voice is so soft it is barely audible, as he explains how he really is quite comfortable with things as they are.

" . . . Being majority leader carries much, much more tensions and pressures. The majority leader is responsible for keeping the Senate moving. pI had to go in and get the thing off the dime, and in many instances, I didn't have the best cooperation from the minority."

He gets up from his desk chair at one point and walks himself across the room toward an ashtray containing a few cigarette butts and, continuing his answer, he walks back to the wastebasket beside his desk, empties the ashtray, and carries it once more across the room to its proper place on the end table, taking care that it is centered on the table just so.

"Now if the Senate is moving at a turtle's pace, it is someone else's responsibility. . . . The Democrats have been a majority so long that it is difficult for them to operate like a minority. But for the Republicans, it was as natural for them to delay the Senate as drawing a breath."

He straightens a chair, fluffs sofa pillows and adjusts a nearby briefcase so that its edges are squared with the edges of the table. He has talked all the while in a monotone, never looking at his guest as he speaks.

"So there is a period in which we have more or less find our bearings, reaching out in all directions. There was a natural state of disappointment and discouragement on the part of all Democratic senators."

The minority leader returns to his desk chair, where he takes out a pocketknife and begins whittling some improvements on his fingernails. He falls into a pattern of slowly speaking a phrase and then pausing. He continues that way, through the next 10 minutes or so of the answer.

"I have to try to be the instrument through which this minority is pulled together [pause] so that it does continue to participate effectively in the legislative process [pause] a force to be dealt with."

Now there is a grand pause.

"And how have I sought to do this," he says, pronouncing what must be a new chapter heading as though it is a statement, not a question. He then goes into a long listing of the various types of meetings that he has convened with regularity this year. Caucauses, meetings of the ranking Democrats on each committee, meetings of the "Class of '82,'' which is comprised of senators up for reelection next year.

Many Democrats have been complaining privately, and some to Byrd's face, that there are too many meetings, accomplishing too little.

A moderate southern Democratic senator on Byrd:

"When you get used to running the trains your own way for so long, it's hard to adjust to a new role . . . . Bob Byrd is . . . having a very difficult time adjusting to his new role. I watch his demeanor . . . . He feels a loss of power.And when you lose the aura of power, you lose everything here. It can damage one's psyche."

A northern liberal Democratic senator:

"If the issue is making the trains run on time, Bob Byrd is okay. But Byrd is not the sort of person that you want on TV representing your party's position. Byrd's self-identity was as the majority leader, the leader of the Senate, and losing the Senate had a far greater impact on him than on anyone else here."

An aide to Byrd:

"'He makes the trains run on time. He makes the trains run on time.' Everyone calls Byrd the man who makes the trains run on time. God, I'm sick of hearing it."

Earlier this year, Byrd paced the Senate floor like a stationmaster whose depot had been dropped by Amtrak. He reported for duty each day in full-dress uniform: ever immaculate in three-piece suits, his vest bedecked with a thick gold chain that starts at the left, threads through a buttonhole (for security) and is affixed to a king-sized gold watch (for punctuality). But this year, the watch and chain have been used mainly for keeping the vest securely fastened.

There were times, in the first two months, when Byrd seemed to feel that he just had to remind people of those halcyon days when all of the legislative trains ran by his gold watch.

On these occasions, much to the embarrassment of his Democratic colleagues and the annoyance of the Republicans, Byrd seemed to take perverse parliamentary pleasure in publicly correcting his Replublican successor as majority leader, Howard H. Baker Jr., on the execution of the Senate rules.

Those were the times when Byrd would rise to announce to the Senate and the galleries that Baker first had to move to waive Paragraph 4 of Rule 12 before he could seek a unanimous consent agreement for a vote, or some such. Byrd was correct, always. But as others in the Senate saw it, that was not the point.

"He could have just sidled over to Baker and said it privately to him," one Senate Repulblican offical said. "But no, he wanted to do it publicly. . . . He took cheap shots, trying to embarrass Baker. . . . But that's stopped now. . . . Byrd is insecure, and these things have a tendency to come out, like in the pettiness of his correcting Howard Baker."

Among those who were the first to sense the tension Byrd felt were the members of his staff. One of the unkept secrets on Capitol Hill is the way Byrd deals with those who work for him. It is talked about, but always quietly and never for attribution, by other senators, by aides to other senators, and by some of Byrd's present and former staff members.

"The way he treats his staff is autocratic, it's chilling," said one Democratic senator from the Northeast.

He limits lunch breaks for his Senate office staff to 45 minutes. He bans personal telephone calls from office phones, except communications of true importance between husbands and wives. He also bans personal visits by outsiders and personal, non-business conversations between staff members. He demands that only clean correspondence be sent out of his offices, and often holds letters up to the light to check for erasures before signing them, and if he finds any, the letters must be retyped.

Last year, his stationery bore the proud legend, "Office of the Majority Leader," and Baker used "Office of the Minority Leader." This year Byrd, forced to face the electoral facts of life, but unwilling to commit to print his minority status, ordered his letterhead changed to read: "Office of the Democratic Leader."

He cannot countenance spelling errors by his staff, being, after all, a man who once read through an unabridged dictionary page by page. And he has been known to sit his staff members down collectively and give them a spelling test.

"I try to treat my staff liberally and fairly," Byrd says. "I work the longest and hardest of anyone in the office." He says he does not ban personal conversations from his offices, for example, but just asks his staff to "keep them down to what is reasonable." He adds: "I was taught to work, and I love it."

In the wake of the election, Byrd is said to have gone through periods of increased irascibility with members of his staff.

There are stories about how he launched into tirades of complaint at the performance of this staff member or that one. One such session is said to have gone on at high decibel levels for more than an hour.

He would say, in those times, that the reason those incumbent Democratic senators had lost in 1980 was because of poor staff work, and he would tell his staff members that they were well-paid and that there were plenty of people waiting on the outside to take their jobs if they couldn't produce. One one occasion he is said to have upbraided a staff member for 10 minutes because there were no towels in the kitchenette in his office.

All this said, Byrd is nevertheless a man who depends to a great degree upon his staff members and makes extensive use of their work. The preparations for his regular Saturday morning news conferences include staff briefings and memos that rival the White House preparations for a presidential news conference. Byrd often recites from the staff memos with uncanny accuracy.

"It's easy, maybe too easy, to put ideas through him and to the public," says one who has prepared some of these memos.

But even those who have confided their unhappiness with the way he has treated them as staff members all add that they believe Byrd to be a truly intelligent and capable man. Says one who admires Byrd's talents, though has chafed under his rule: "The profoundly said thing about the man is the overwhelming insecurities and doubts."

"To understand Bob Byrd you have to understand his background," says one who has worked for him. "The scars never healed"

The observation is made by virtually everyone who is asked to discuss the man. Robert Carlyle Byrd was born Cornelius Calvin Sale Jr., a fact he did not learn until he was 16, when he was told that his real mother had died of influenza when he was an infant and that Vlurma and Titus Dalton Byrd, who had raised him as their own, were really his aunt and uncle.

Byrd's birth date was Nov. 20, 1917, a fact he did not learn until 1971, when an older brother contacted him to offer congratulations on his unseating of Sen. Edward M. Kennedy as Democratic whip.

The Byrds lived in a poor coalmining community. Byrd did not live in a house with running water until he was 21. Throughout his childhood he had one toy, a car he could pedal and ride. He kept it until adulthood.

His country origins led him to his one adult diversion in life: he plays the fiddle. He takes his fiddle with him when he campaigns, and he commands his audiences into silence even at those $1,000-a-plate Democratic fund-raising soirees, a source of irritation to many of his colleagues.

He also made a record album of country and bluegrass music, of which he was very proud and pushed its sales in his office. He was especially proud when one Washington lobbyist said he wanted to buy 100 records to give away as gifts. Byrd suggested that it would be nice if other lobbyists also wanted to buy his records. About a dozen lobbyists were convened for a special luncheon, which included the privilege of listening to Byrd speak and play his album, and the promise in advance that they would also buy about 100 copies each.

Byrd has heard for years the observations of armchair psychiatrists about how so much of what he is stems from his lean origins. He is asked, near the end of an hour and a half interview, about his view of the effect of his background on his present life.

"Well," he says, "As Tennyson said, 'I am a part of all that I have met.'"

This leads, then, to the obvious question about the most controversial of all that he has met: his membership in, and organizing in behalf of, the Ku Klux Klan in the early 1940s, and its effect on his life today.

Suddenly, Byrd's face freezes. The muscles on either side of his jaw harden to what must be the consistency of golf balls. His eyes are lasers burning deeply into his questioner.

There is silence.

"I really do not want to answer that question," he says finally. "It is something I have addressed time and time again." He is tired of hearing about it, he says. Tired of having to answer for it. It was just a mistake of youth, he goes on. "Just as a lot of young people these days join organizations they regret joining, I joined as a youth and regretted it later. I made a mistake."

Byrd says that all he has to say about it is in the old newspaper clippings.

The clippings show that at age 29, Byrd, as a former Kleagle, wrote the Imperial Wizard of the Klan saying, "The Klan is needed today as never before . . . "

Asked again if he would like to say what he thinks of the Klan today, he explains: "I abhor the Klan. Every time I see on television men wearing robes, it turns me off. I took upon the Klan as a silly, asinine group that tries to act outside the law, and uses violence and intimidation as their currency.

"It is utterly silly and juvenile: a guy out there with sheets on trying to intimidate and threaten violence. My face turns to flint at violence."

Constructive criticism is one of those things that it is better to give than to receive. During one of those private Democratic caucuses not long ago, Byrd made it clear that he figures he has been on the receiving end of just about enough.

An elder of the party, Sen. Russell B. Long of Louisiana, once delivered a sermon on the effective management of Minority Leader Lyndon B. Johnson when the Democrats were briefly out of power in the early 1950s. At the next caucus, two weeks later, a younger senator, Max Baucus, the first-termer from Montana, picked up the theme and elaborated on it at length.

"Well let me tell you something," Byrd interjected. His voice was soft, but his gaze was hard, according to other senators who reconstructed the conversation weeks later and who attest to its general accuracy if not its precise wording.

"I'm not Lyndon Johnson, and these are not Lyndon Johnson's times. If Lyndon Johnson were leader now he wouldn't be able to operate as he did then. What worked for Johnson won't work now."

In his fifth year of leadership, Byrd remains an enigma to his fellow Democrats of the Senate. They understood the arm-twist and braggadocio of Johnson, and they understood the quiet countenance of his successor, Mike Mansfield. But they do not really understand the man who leads them today.

"I don't know what makes Byrd tick," said one southerner who has been mentioned as a challenger to Byrd, who remains his critic, but who says he has no intention of making the move. "Byrd has never felt as secure in his position as he should.

"Having said all that, I would not vote in 100 years to replace Bob Byrd as leader. . . . When you talk about replacing Byrd, you couldn't get three votes."