IT IS 92 DEGREES and climbing in rural South Carolina as Nancy Thurmond, the 31-year-old wife of 75-year-old Strom, piles out of "Strom Trek." The white camper is decorated with blue and white stars and stripes and Thurmond's picture fore and aft, and inside are red, white and blue washcloths with an American eagle and colonial flag decal. She plans to further decorate the inside of the camper with "patriotic type things." At all times during a week, some of Thurmond's four children - age 2 to 7 - are with her in their special T-shirts. Names on front and, plastered on the back, a message: "Vote for My Daddy."

Nancy Thurmond, hands clasped in front of her, explains "Strom Trek" to her audiences inone of her oft-repeated sentences. "Just as the spaceship 'Star Trek' went out in the galaxies bringing good will, we go over the rivers and through the woods spreading good will to the people of South Carolina."

Nancy Thurmond moved the family to South Carolina a full year ago to start campaigning.

Her litany emphasizes Strom's absence. "He's up in Washington doing his work and he's got his family out campaigning for him." When Paul, age 2, is too overcome to walk the streets, Nancy is undaunted. She points him out to a trio of townfolk invited into the camper. "There's little Paulie up there sleeping."

Nancy Thurmond dismisses the thought of any political exploitation. "Why, I just want to be with my family! I don't believe in leaving them home." Her smile is perky as she smooths her sprayed shoulder-lenght frosted hair."I just believe in helping Strom in my own little way. . . ."

Then in a time-forgotten town by a railroad track, she hits the ground running, deploying the troops everywhere. "Now Nancy Moore," she commands her 7-year-old, "you go uo that street," and tells an aide to take Strom Jr., 5, with her down the other side. Nancy Thurmond herself peels off for the post office, hand outstretched. American flags and a family recipe book - with pictures of the Thurmonds on every page - are handed out.

"How y'all doin' today?" "So nice we could visit with you. . . ." A woman's dress shop is "just the cutest place." A supporter's home is "just fabulous. " A baby is scarcely glanced at before Nancy Thurmond enthuses, "I just LOVE Eddie - he's a FINE baby."

Back in the camper after a Strom Trek blitz that kept to an exact five-stops-in-an-afternoon schedule, Nancy Thurmond meets up with the children and aides. Her first question: "How did Strom Jr. DO? " The Personal Touch

Molly Ravenel, slim, tan, dark-haired, 36-year-old wife of Charles "Pug" Ravenel, Strom Thurmond's 40-year-old Democratic challenger, moves around South Carolina in stylishly long summer skirts.While Pug hits other parts of the state, Molly does her own campaigning.

She introduces herself in a lilting voice, easily makes small talk but soon launches into issues. She talks in detail about her husband's proposals for "alleviating" problems of inflation and unemployment, energy and social ills. She blasts Thurmond's voting record and says that if her husband had not run, "I find it appalling that Thurmond would go 12 years without a challenge." She is at ease in a question-and-answer forum. There are no children along. She wanted her three children, ages 9, 8 and 5, to have a "normal" summer of day camps and swimming. She is out three days a week. She pointedly jokes that there is not one family picture in Ravenel's 12-page issue-packed brochure. She refrains from openly criticizing Nancy Thurmond - who has ignored Molly when their paths cross. "I always have to make the first move," says Molly.

Instead, Molly Ravenel points out that many polled view her husband as young, attractive, energetic, dynamic. She then steps in, "I don't need to have my children out campaigning - and neither does Pug."

South Carolina has prided itself on being independent from the days when it voted for Al Smith over Hoover. Today, young, progressive candidates have toppled old establishment incumbents in many of the state's top offices. For one thing, blacks are voting in increasing numbers and old segregationists who used to "out-nigger" one another are scrambling for their votes.

Anomalies, however, abound. TV media campaigns have made it easier for virtual unknowns to bypass effectively the disappearing network of machine-controlled politics. And yet, in a state where some newspapers continue to print deaths and births on the front page, the personal touch is still prized.

The vagaries of South Carolina politics make it difficult to predict in fact what the "people" will do. The Democratic nominee for governor, Dick Riley, is a case in point. The number who would vote for him was too small to even register on a November Peter Hart poll. In April, Riley had but 13 percent of the vote and he went into the primary badly trailing the front-runner. He won by 20,000.

One reason for indefiniteness is the "gentility factor" of Southern expression. "In New York, it's easy to figure out. Everyone hates everybody," sighs Marvin Chernoff, Ravenel's top consultant and a transplanted northerner. "But down here, everybody just loves everybody."

Ravenel, the underdog, gets a rating of everything from a "no chance" to "anyone who counts him out is a fool" as one travels the state. He is anywhere from 7 to 16 percentage points behind in various polls. Ravenel won 56 percent of the vote in a five-man primary - his nearest opponent got 19. He is banking on a majority of the 25,000 new voters in the state since 1972, Thurmond's last race.

His slogan: "All I need is 50 percent plus one." The Old and the New

As Mizz Thurmond and Mizz Ravenel - as they are called in this Deep South enclave - travel the state, there is more at play here than just a difference of style between political wives. They are a significant part of and exemplify a well-defined strategy in a campaign billed as a true test of Old South Politics versus New. At first glance, the Thurmond-Ravenel clash does seem the embodiment of such a stereotype.

Thurmond is an institution. The tubthumping relic of a faded fraternity of segregationists who retained national office through unflagging devotion to box socials and favors for the old courthouse crowd and everybody's aunt, uncle and cousin, Thurmond doesn't miss a funeral or a wedding. It has been said that he could strike up a conversation with a door knob.

A Riley aide recalls in fascination: "I am 29 and when I graduated from kindergarten, Thurmond sent me a personally signed copy of the constitution. From grammar school, it was the Declaration of Independence. From high school, it was the flag."

Ravenel, on the other hand, is the new breed. Harvard educated, a former Wall Street investment banker, he stunned the establishment by winning the gubernatorial primary four years ago as an "outsider." (A court ruling that he failed to meet a five-year residency requirement kept him out of the general election he was heavily favored to win.)

There are, however, underlying complexities.

For example, a growing anti-Carter sentiment makes his endorsement of loyal supporter Ravenel a debatable factor. A Ravenel fund-raiser with Ham Jordan as its centerpiece last week was a bomb by some observers' accounts, with less than 50 attending. (Ravenel aides say they made $4,000 from two Jordan appearances.) Some supporters are even urging Ravenel to extricate himself from a September $1,000-a-plate fund-raiser with Carter, while others still see it as a plus.

Blacks now account for close to 30 percent of the vote in South Carolina and one thing Thurmond was always able to do was count. The man who led the Dixiecrats and said "there are not enough laws on the books of the nation, nor can there be enough laws, to break down segregation in the South" has gotten media mileage out of sending his daughter to a public school that is 50 percent black and, after 23 years of opposition, supporting full D.C. representation. Thurmond in the last four years had done enough favors for black universities and leader to gain considerable support. "It (Thurmond support) is not the prevailing attitude in the black community - but it doesn't have to be," predicts Jim Clyburn, the state's Human Affairs Commissioner who was favored to be the first black state official since Reconstruction. He just lost out in June's primary as Secretary of State to a white, and some disillusioned blacks - who feel some white Democratic leaders thwarted Clyburn's chances - are also threatening to go Republican and vote for Thurmond.

The black vote is pivotal - some predict Ravenel needs 90 percent of that vote to cut successfully into Thurmond's entrenched constituency.

Finally, images are definitely not what they seem. Thurmond's down-home style masks a formidable, slick, well-financed "new politics" campaign. His supporters are fond of painting Ravenel as the Yankee carpetbagger media man with outside support. But it is Thurmond who has tied up heavy blocks of prime media time for late September and October. And who has received by far the majority of his campaign money - some $1 million to date - from such decidedly out-of-state centers as New York and California? Thurmond - largely through the sophisticated efforts of rigt-wing direct-mail czar Richard A. Viguerie.

Pug Ravenel is flying home to Charleston in a two-engine, four-seater private plane after 48 hours of campaigning and three hours sleep. The energy, the enthusiasms are still there as he talks about life and literature, about himself and politics. The Gulpers and the Sippers

"I'm a risk-taker. I never had much . . . and never had anything to lose. You don't ever get anything unless you make yourself vulnerable." There is a buoyant rage for living as Ravenel says, "In this world there are gulpers and sippers. I'm a gulper."

Ravenel is an old-line Charleston name and Edna Ferber took it for her riverboat gambler, Gaylord Ravenel, in "Showboat." Ravenel jokes that he is one of the poorer, "black sheep Ravenels."

His past belies the rich, preppie image that Thurmond supporters push in rural South Carolina. His father worked in the Charleston shipyards and Ravenel started delivering papers at age 12.

At Harvard, Ravenel played football well enough to get an All American mention, even though he is barely 5-feet-8. Ravenel stops in th emiddle of a street when someone comments on his size, and makes a muscle under his rolled up Ralph Lauren shirt."Just look at that!" Then he laughs. "My football career functioned on sheer terror."

Later, seriously: "The reason I played footabll has a lot to do with what drives me. We're a product or a function of all those psychological forces within you, and you never know what they really are. Well, I was small. When I got my driver's license at age 14, I was 4-feet-11 and weighed 98 pounds. And I wore glasses. And growing up in a culture where manliness was prized, this was a real putdown. I had to really reach to overcome being afraid all the time, and so I became athletic. I used to hang from a bar in my backyard, trying to stretch. I had dreams of being 6-2 and 190 pounds. I played basketball and ran track and played baseball." (He won the nickname Pug when he dove for a line drive and missed and broke his nose). Friends now give him pictures of Napoleon - for his Napoleonic complex - and he got three copies of "Short People" for Christman.

Ravenel has a slight southern accent, dropping the g's on endings. "In high school I was disgustin', absolutely disgustin'. I went to a Catholic school and was unbelievably straight-arrow. I used to charge people money for cussin' in my car. Anybody who cursed I charged 10 cents - had a cup right on the dash board. I was so ridiculous."

A scholarship to Philips Exeter took Ravenel into another world."They were trying to change their eastern preppie image. They went to newspapers around the country and asked about newspaper boys. I guessed they figured you had the need and that extra oomph." Ravenel wrote home about the wonders of the liquid soap dispensers in prep school bathrooms.

At Harvard, Ravenel held four jobs at once and played football. "I sold clothes, delivered papers, slopped food in a kitchen, referred ball games, drove a launch. I hustled my a--off since I was 12 and when I got out I wanted to make some money for a change."

He did, on Wall Street. "I lost it all in 1974 (in the governor's race) and I made some of it back. I'd say my net worth is about $150,000 now, mostly raw rural timber and farm land."

Along the way, Ravenel met Molly Curtis - the daughter of a well-to-do Connecticut lawyer, a product of Farmington, Jackie Onassis' school when it was known as Miss Porter's, and Smith. She studied one year abroad, majored in history and English, did her thesis on Edith Wharton, taught French.

"I just flat fell in love, but she also was the kind of person I thought I might want to marry. She was intellectually my superior, independent. But Molly represented as well . . . how can I say this? She had a sense for gracious living that was part of her upbringing and was appealing to me. I like her taste. Her sense of the 'fine' and not the garish. I like her solid substance."

A close friend says, "Pug's more fun - he's got this great ebullient sense of humor, but Molly is incredibly kind. She always had this sense of maturity to her and cares about the important serious things."

Molly introduced Pug to the classics and now he quotes - either from notes on his schedule book or from memory - lines that spellbind him. "There is this Norwegian author, Knute Hanbsum, whose writing is stunningly beautiful . . . Edith Wharton's 'Ethan Frome' is one of the greatest books. . . ." The Ay-triculate Candidate

A hostile crowd of businessmen of the Graniteville Exchange Club stared blankly as Ravenel quoted Oliver Wendell Holmes:

"Holmes said, 'You fail to involve yourself in the actions and passions of the times at the peril of not having lived.'"

Despite his intellectual approach, Ravenel has a reputation as an impressive speaker and media figure. In great detail Ravenel speaks of his fiscal conservatism and social progressiveness. He talks to blank faces about the "mosaic" of reasons that "impel me to run." He refuses to lighten his vocabulary, as has been suggested. His wife jokes that only three people will read his issue-choked brochure - "me and Pug's mother and Sen. Thurmond." When Ravenel finished speaking, one textile mill foreman said, "He's for labor reform and that's too damn liberal for me, but one thing, that feller is ay-triculate."

They listen attentively when he talks of inflation. He wants a three-year freeze on government spending, and business incentives to put people to work.

"We spent in the last 10 years $50 billion to get at the hardcore structurally unemployed. Fifty billion! And in the face of that the structurally unemployable has risen dramatically. Instead of paying $12,000 to have the government provide a job, why not give $10,000 to a private company to hire that person. And it becomes a real job. I think my solution is certainly worth a try."

Above all, Ravenel hammers away "like a carpenter" at Thurmond's record. "He is running on his record. Well that record in terrible.

"A legislator is supposed to get legislation enacted.

"In five years he introduced 170 pieces of legislation.

"He got seven passed and that's a failure rate of four times of just your average senator.

"And nothing raises the hair on the back of my head more than to hear him stand up and say he's done more for South Carolina than any one else. We're 38th in receipt of federal dollars. He used his seniority - such as it is - to BLOCK the flow of federal money into this state. He voted against $189 million worth of education funds that came to this state in the last three years, against comprehensive health care centers. Then he makes a big symbolic thing of announcing some grants to some black universities. . . ."

There are, of course, intramural politics at play that have little to do with the merits of Ravenel vs. Thurmond. Ravenel's start at the top seems too audacious to garner support from many establishment Democrats who still smart at his refusal four years ago to endorse William Jennings Bryan Dorn, who took Ravenel's place for governor. Ravenel says that would have gone against his ideals as an anti-establishment campaigner. Dorn, a venerated old-timer, now smiles and refuses to mention Ravenel's name when he says he's 'endorsin' the Democratic ticket."

As he talks of his future, Ravenel seems a cross between a shrewd, confident businessman-politician and a naive, eager challenger. He says he always intended to return South Carolina. He dreamed of a political career since he was 16 but waited to run until he could make enough money "to afford to be independent. Some say I should have started lower down the line - but I believe in running on merit." In the next instant he says, "Just think! The United States Senate! It's like a Little Leaguer making the World Series. Politics is the highest calling."

If he loses in November, some South Carolina politicians ar already nailing the coffin shut on his political career. As Ravenel crisscrosses the state, shaking hands - "Hi, may I introduce myself . . . I'm Pug Ravenel and I'm running for the United States Senate . . ." - trying to convince people "I am a real human being," Ravenel feels it all ultimately boils down to only one thing.

"Thurmond's strategy is 'I did you all these favors. Send me back.' My strategy is 'We've got some serious problems in this country today. I can do a better job in the next six years than he can.' Now if the world turns on personal favors, he's gonna win. If the world turns on the issue of who can do the best job, I'm gonna win."

It was hard to tell if his next thought was born of conviction or pure bravado. "I have faith in the voters of this state." 'Mother's Medicine'

Nancy Moore Thurmond met the senator when she was crowned Miss South Carolina of 1965, and Thurmond called to congratulate his constituent. She went on to graduate with honors from the University of South Carolina and was going to law school when Thurmond asked her to marry him in 1968.

"I always say 'Well, I loved law school but I loved him better.'" Nancy Thurmond is bright and ambitious, and the feeling among both Republicans and Democrats in South Carolina is that if Strom should die in office, his wife would step in. Before she can be asked about that, Nancy Thurmond interjects, "I'm not interested in politics for myself atall . I'm just glad to help Strom in my own little way. I do a lot of volunteer work but I have a 20-year career raising these four little children. And I always have just beaucoups of paper work, thank-you letters and all to write."

Two young women live in full time to help with the children, the laundry, the cooking. But Nancy Thurmond has written a book called "Mother's Medicine" filled with child-rearing tidbits that will be published in the fall. "Oh I can't believe Strom told you about the book!" she says when it is brought up. "The section on nutrition is called 'Food for Thought,'" she says solemnly.

The section on babies and diapers is called "The Bare Essentials." The child is always referred to as "he" in the book. On sex: "Introduce him to the facts of life through nature." On organization: "If your son has 19 mismated socks, you are not organized." Fathers should play a "game of ball with the little fellows." When a child is sick, Nancy suggests a special blessing: "Dear God please make (blank) all better so he can go out in his coat and sweater. . . ."

On the Strom Trek, complete with running noses and milk sliding off the table at sharp turns, Nancy Thurmond remains unruffled. Blessings are said before downing Hardee hamburgers. When Paul cries and dribbles popsicles on her blouse, Nancy Thurmond calmly puts him down and continues her spiel to some men at a gas station: "Hope y'all vote for Strom in November." The children tend to get whiney. Strom Jr. is propelled forward in one hardware store by an aide: "This little boy is Strom Jr. and we've come to say 'Hi.' What do you want to say to these folks Strom?" Strom Jr. says nothing. The aides pushes the brochures in his hand, then turns Strom Jr. around so they can see 'Vote for My Daddy.' "Well his shirt says it all."

At one point, Nancy Moore strikes a set pose for the photographer. "Now don't you go giving him your fakey old grin," says her mother. The grin remains the same. Her mother whispers to her to stop it. "I can't help it," says Nancy Moore. When a visitor gives Paulie a popsicle, his mother holds it slightly out of reach. "What do you say Paulie?" He is about to cry. "What do you say Paulie? What do you tell the lady?" He mumbles thank you and gets the popsicle.

When someone asks how the children are bearing up through a summer of campaigning, Nancy Thurmood emphasizes "They're just normal little kids." At a nursing home, Nancy Moore backs away from a bony old woman who wants to hug her. "Hug the lady," commands her mother wit a smile. She does.

Through two days of travel there is nothing but the most even of smiles; the voice is unraised. Nancy Moore says, "Oh momma gets angry sometimes. She gets sorta impatient. But she doesn't show it in front of guests."

At 31, there is still a doll-like look to Nancy Moore Thurmond. Her round face with the blue eyes has the faintest trace of an incipient double chin. On the hottest of days she wears nylons. "You do have to be careful about your appearance." There is nothing faddish in her dress.

Above all, there is this awesome discipline, the model stance left over from beauty contest days. At one courthouse she stands with one foot slightly in from of the other, arms in front, hands together. A man is telling her that his aged mother had died. Something seems out of sync. The happy smile never wavers as she says, "I wish there was something that could relieve your suffering." (There is a photographer about 10 feet away taking her picture.)

Thurmond supporters rave about how Nancy Thurmond is a "definite asset. She's bright and pretty and makes a good appearance." No one asks her about issues. When a reporter presses, her answers are like her husband's. His segregationist stance? "You've got to remember, that was the law then." His heavy defense spending? "He's for the military might of this country."

Whenever there is talk about his record of opposing federal programs that would aid the poor and uneducated in a state with the highest illiteracy rate, Nancy Thurmond says that her husband is voting the wishes of the people of South Carolina. The Equal Rights Amendment? "I think what women wanted to achieve through ERA has been achieved. Women have more rights today than they ever did."

Only once in two days did Nancy Thurmond reveal any inner thoughts. Asked what angered her, she said in a thin, even voice, "I never get angry about anthing." There is no smile this time. "I've been through campaigns before and I know what to expect." She stares coldly and directly at her interviewer. "I can probably read you the Washington Post article before it comes out. I can second-guess things. So it doesn't bother me."

Age is the one whispered issue in this campaign. Ravenel knows there would be a sympathy backlash if he attacks Thurmond as being over-the-hill so he talks instead of the need for "new solutions" to "new problems." Touring the state, one finds concern about his age among "soft" Thurmond support. Many others say they think it's time for a new man.

On the Hill, colleagues talk about Thurmond's "not being sharp on some issues some days" but no one will say it for the record.

No one is more aware of this talk than Nancy Thurmond. When age is brought up, she always says that she's the one who gets tired and "it's just so hard to keep up with Strom." There are some good ole boy snickers when the children are paraded through rural gas stations but it still connotes a macho virility that impresses some.

Nancy Thurmond, whose own parents are younger than her husband, says, "If his age had bothered me I would have never gotten married in the first place." The realization that she will doubtless have to raise some the children alone "has not crossed my mind. Our marriage has lasted for nearly 10 years and outlasted most of our friends'. Oh, I've had some hilarious things said. Just hilarious. Like are you Strom Thurmond's daughter? I'm just thankful they don't say granddaughter. And, oh, I just laugh. I guess you might say public relations is my field.

"Now little Nancy Moore, who is 7, has kinda fallen for one of the young men on the campaign staff. She says how cute he is and I said, 'Nancy Moore, he's entirely too old for you,' and she says, 'Mama, he's only 12 years older than I am.' Well, I tell you, I just get onto another subject." He'pping Constituents

The Thurmond strategy is to stay tucked away in Washington during the week and hit the state on weekends. At one politician-filled festival, when Strom finished speaking, his children raced from the wings on cue and, as one observer expressed it, "attached themselves to him like jellyfish to a swimmer."

Ravenel has tried to smoke Thurmond out for a debate but Thurmond refuses. "Let him draw his own crowds - we're ahead," says Thurmond.

He bikes and jogs with the children and when asked about the age factor says, "I can still stand on my head."

One Sunday night he attended his zillionth public gathering. Some 200 people has showed up just outside Columbia for the opening festivities of the Dixie Youth Baseball Tournament. The parking lot was filled with pickups, and a voice twanged on the loudspeaker, "I'd like to welcome y'all."

Strom flaps away the gnats and holds his baseball cap over his heart during the National Anthem, then fires off a rousing, patriotic speech about how competition "has made America great."

After, Strom attacks the crowd with the two-hand politicians' arm lock - one at the elbow, the other grasping and pumping the hand. Over and over, "Glad to be with you . . . good luck to y'all." He spots one of the uniformed players, a tall black youth named Cozard Carr and races over just as the photographer takes pictures. "Good luck, son," says Thurmond. The young man looks perplexed.

Thurmond, the past master of constituency service, leaves a trail of faithful who remembered "how he he'pped us." "He got me my alimony check." "I wrote him about my social security and he he'pped." "He got me my disability check." It is this sort of politics that some predict will sink Ravenel. Thurmond says "Shakin' handd and doin' favors is just part of my life."

His single most important accomplishment is 24 years in the Senate, he says, was "getting beautiful brick buildings" built at military bases in Charleston and Fort Jackson.

Thurmond has a one-page brochure with no statistics. It plays up his stance against federal spending and the need for military might. He answered questions with short generalizations. The labor reform bill is a bill to "unionize the South." Last spring, he milked the Panama Canal the way he used to milk segregation - shouting about the treaty "giveway" and charging that "Cuban guerrilla forces are being trained in Panama for a possible takeover of that country."

For all his change on racial issues, Thurmond still speaks patronizingly. "People in the South generally like black people . .. worked with 'em in the fields and stores. They understand 'em and help 'em." Ravenel charges that Thurmond's true feelings come out "like sweat out of pores" and points to one of Thurmond's statement on Medicaid abortions, which would benefit the poor blacks in the state. (Ravenel favors including them in all cases, Thurmond only in cases of rape or incest or for women whose health is endangered.) Thurmond's quotation: "Just to get pregnant and have an abortion may provide a lot of fun but it's not very good."

Nancy Thurmond is asked what she would do if her husband were defeated. "Why, I don't see any way that is possible."

Then she stops to ponder her own future. "If anything ever happened to Strom, I'm sure I'd marry someone else my own age. So I didn't have a fixation for an older man as some may have thought."

The smile is in place. "Strom's just so very unusual."