It comes to this in politics sometimes -- a poultry farmer finds a way to convert chicken droppings into electricity, so he erects a big white circus tent in the midst of his pasture land and hosts a celebration. Chicken farmers flock from miles around, local sheriff's deputies direct traffic off the highway and politicians swarm like flies from far corners of the state. There are county commissioners, water district officials, a mayor or two, a congressman -- and even Sen. Sam Nunn (D-Ga.), widely regarded as the most influential person in Georgia and one of the most influential in Washington.

Arriving a few minutes late, Nunn steps from his car wearing a banker's pin-striped suit and buckled leather shoes. He pumps a few hands and embarks on a walking tour of the fetid farm, striding briskly ahead like a man who takes his chicken manure seriously.

And he is serious -- while the other pols lag behind, sniffing the air and exhausting their repertoires of manure jokes, Nunn interrogates his guide intently. He wants to know how the manure system works, whether it is economical without government subsidies, what kind of energy it produces -- on and on and on until the arcane details of manure conversion threaten to bury him up to his owlish glasses.

"Are you going to show us where you collect the waste?" Nunn inquires impatiently at one point. It is a question no one else has been inclined to ask.

"We can, yes. It's around back," his guide replies.

"Good." Nunn pauses. "I'm used to that smell." His humorless voice lingers awkwardly; it isn't clear what he means.

But a few minutes later, Nunn abruptly strips off his veneer of solemn manure scholarship. Standing now at the podium inside the big white tent, he rocks the overflow crowd with a joke about a "big-city politician" who visits a farm and steps in some manure. When the politician looks down at his feet, he says, "Oh my gosh, I'm melting."

The farmers laugh and nod and clap. It is a poignantly familiar scene -- the country tent, the wisecracking Baptist preacher who earlier praised God and free enterprise and now the distinguished senator warming to broad themes of Old South populism.

There is deep irony here. Sam Nunn is hardly a good old boy, and no one in Washington would confuse his hawkish, detail-driven politics with populism. And his life style -- his big house in suburban Bethesda, his weekend golf foursomes at Congressional Country Club, his presidency (in 1984) of the elitist, men-only Alfalfa Club -- is far removed from the back-roads world of north Georgia poultry farming.

In fact, it is precisely this contradictory character that makes Nunn, at 47, such an interesting and effective politician. He has done what Jimmy Carter never could -- he has spanned the wide cultural chasm between his origins in Georgia and his life now as a consummate political insider.

Last week, for example, he emerged as a major force in the dispute over Philippines policy, accusing President Marcos of "massive fraud, intimidation and murder" just as President Reagan's "hands-off" posture seemed to be solidifying. (The administration has since become more critical of Marcos.) Nunn's sweeping Pentagon reform plan, unveiled last fall, and his familiarity with the minutiae of defense spending have placed him at the center of the Gramm-Rudman-Hollings budget debate. And, increasingly, he is the subject of talk about the vice presidency in 1988.

Like Carter, Nunn catapulted himself into national political life by exploiting his rural roots in a campaign against "the establishment." But unlike Carter, he has learned to operate effectively inside that same establishment. Along the way, Nunn has become the antithesis of the modern media politician who, with the help of admen and consultants, reinvents himself to appeal to a shifting national mood.

Instead, Nunn has devoted himself to building long-term personal relationships with his colleagues in the Senate -- relationships that pay off in clout inside his "club."

He "made sure he understood everything that was going on in his committees and in the Senate, and because of that he's become very well respected," says former senator William Hathaway (D-Maine). "In the committees, in the cloakroom, he was one who got along with both liberals and conservatives. When I was in the Senate, I considered him one of my closest friends even though we didn't see eye-to-eye on a lot of issues . . .

"You know the phrase: When he talks, people listen."

From small-town Georgia to big-time Washington, Sam Nunn has built a bridge to power. The story of his rise is a study in achieving influence the old-fashioned way.

On the day they voted him down, the members of the Georgia state legislature hung a painted sign inside the Capitol to proclaim the news: Sam Nunn was finished.

"Bye Bye Nunn," it said in big, gleeful letters. Some of the legislators were so happy that when the final vote came in, they stood up and took out their handkerchiefs and began to wave at Sam Nunn, singing, "Bye bye, Sam, bye bye . . . Bye bye, Sam, bye bye . . . "

It had been an especially bloody session in the always volatile Georgia statehouse -- it was 1972, the year the census numbers came in and the legislature redrew every political boundary in the state. Nunn was a newcomer to the legislature, just over 30 years old, but he had managed to insert himself behind the scenes of the redistricting fight, spearheading a plan to create a congressional district centered on his hometown of Perry, 100 miles south of Atlanta.

He had been planning for years to run for that seat in Congress and now, on the verge of his triumph, it had been snatched away. After months of deal-making and lobbying and tinkering and pleading, Nunn's redistricting plan had lost out to then governor Jimmy Carter's.

"Bye bye, Sam, bye bye."

The frustration he felt over his defeat ran so deep that it provoked a change in his basic character -- from cautious, dull solemnity to foolish irrationality. At least, that was how it seemed to his friends and advisers when Nunn announced he would run for the U.S. Senate.

He had precious little chance at winning, of course -- his own poll revealed that only 2 percent of Georgians had ever heard of Sam Nunn. "And I don't think even half of those are for me," he quipped to an adviser when the results came in.

One night he sat down with his wife Colleen, took out a legal pad and made a list of all the reasons not to run, which were numerous. Beside that list he wrote down all the reasons why he should run, which were not many. Then he threw away the paper and told his wife, "There are two choices now. One is to run and find out what will happen. The other is to not run and sit back and be haunted by it the rest of my life."

What was Colleen to say?

Others in his family were not so deferential. His great-uncle, the late and legendary representative Carl Vinson (D-Ga.) -- then chairman of the House Armed Services Committee and a four-decade veteran of Congress -- told his backers not to bother contributing to nephew Sam's campaign. The odds were too long.

Nunn drove himself around the state in a gray Pontiac, trying to stay awake on three hours of sleep a night. He was alone and sometimes he was afraid; he had yet to conquer an intense fear of public speaking that had been with him, to varying degrees, since high school. In law school, not many years before, speaking to a room of people had been "just agony. I mean, just standing up and making a five-minute talk . . . "

Now he was speaking several times a day, and sometimes the fear would come again. Around midnight, he would be driving by himself down a black Georgia highway, maybe thinking about a speech he had to make or maybe just trying to play cerebral games to stay awake. One night it didn't work -- he drifted off to sleep, his foot slipped off the accelerator, and the car began to veer off the highway.

When he woke up he was driving right at the abutment of a bridge.

He stopped in time, pulled off the highway, and told himself he had to find a college kid to drive his car.

After months of this grind, Nunn scraped up enough votes in his crowded primary to earn a runoff against David Gambrell -- a wealthy Atlanta lawyer who had been appointed by Carter to serve out the term of deceased Georgia patriarch Richard Russell. Carl Vinson, won over by his nephew's demonstration of political stamina, jumped on his bandwagon, and Nunn ran a savvy campaign against Gambrell, playing on the suspicions rural Georgians have always harbored about anyone from Atlanta.

Nunn also campaigned against the unchecked power of federal judges -- a thinly veiled stance against federal desegregation orders. George Wallace endorsed him, as did renowned segregationist Lester Maddox. But black Georgia state legislator Julian Bond supported Nunn, too -- a fact the candidate did not prominently advertise during his campaign.

He won the general election easily.

"I don't think anybody -- including Carter and anybody's who's ever run -- worked as hard as I did during that period," he says now. "It was something else. It was a marathon."

Sam Nunn is described by many of his friends in Georgia and by the young lawyers and economists who have worked for him in Washington as a brilliant but "remote" man. If you worked for him, you never sauntered into his office and shot the breeze about political gossip or basketball (he was an all-state guard in high school) or even the subject he cares most about: defense. His wife once said that Sam Nunn "doesn't have a whole lot of idle thoughts."

"I think that was her way of calling me stuffy," he says.

He can see the ways in which his detached and serious character traces directly to the men who were around him when he was growing up -- especially to his father, who was 50 when Sam Nunn Jr. was born. The late Sam Nunn Sr. was a prominent lawyer and landowner in Perry. He was also a diabetic plagued in his later years by recurrent ailments. Sam Nunn Sr.'s great -- some said his only -- passion was reading. Toward the end of his life, he stayed in his study off the parlor and read virtually around the clock. He was especially fond of books about the Confederacy; his wife remembers him reading "Lee's Lieutenants" seven or eight times.

"His father was a very formal man," recalls Virgil Peavy, a close boyhood friend of Nunn. "When I was in their home, I didn't feel like the relationship was as warm as it was in my home."

Nunn believes his father's advanced age was significant "in the sense that we didn't go hunting and fishing. We weren't buddy-buddy from that point of view. He was more of an example than a close -- we were close, but it wasn't like my son and I, we do things together all the time."

There were other men who were important to Sam Nunn -- men who were, in some ways, like his father. Carl Vinson came back from Washington to attend Thanksgiving dinner every year at the Nunns'. Former senator Herman Talmadge (D-Ga.) also stopped by the house from time to time. Sam Nunn Jr. absorbed a great deal from the conversations with these Georgia kingmakers that passed in his living room. "I'd sit there and I didn't get involved in it very much," he says. "I just always listened."

The men around him did more than influence Nunn's character; they also helped shape his career. After Nunn was elected to the Senate, his first trip to Washington was a train ride with his great-uncle. Vinson escorted his nephew to meetings with some of the most powerful men in the Senate -- Talmadge, of course, and Sen. John Stennis (D-Miss.) and former senator Henry (Scoop) Jackson (D-Wash.). One result was that Nunn secured a seat on the prestigious Senate Armed Services Committee. The committee is an important source of political strength in Georgia, which is home to a number of major defense contractors and a large military population. "He immediately made the contacts," recalls Rep. Richard Ray (D-Ga.), who was Nunn's administrative assistant for 10 years. "He kind of sailed into that Armed Services Committee."

"People like Stennis and Jackson -- I stayed in constant touch with them," Nunn recalls. "I didn't talk to them in general about, 'How do you conduct yourself?' but just about what they thought about the issues. And by the time you get through talking to them about those things, you generally pick up by osmosis their views about how senators should conduct themselves."

Nunn responded to his mentors with deference and hard work. If he voted against one of them, he did it quietly and only after direct consultations. "Sam didn't get in any downright confrontations," says former senator Robert Taft (R-Ohio), a colleague for two years on the Armed Services Committee. "He didn't reduce matters to personalities." And by avoiding confrontations, he made friends with senators as politically diverse as Barry Goldwater (R-Ariz.) and Edward M. Kennedy (D-Mass.). His friendship with Goldwater, who is today chairman of the Senate Armed Services Committee, has permitted Nunn to advance his military reform agenda even with his party in the minority. Last fall, with Goldwater's blessing, Nunn introduced the Pentagon reform plan that has placed him once again at the center of the defense spending debate.

But there was more to Nunn's rapid, quiet rise inside the Senate than the caution and respect he exhibited with his elders. There was also his unquenchable fascination with the minutiae of defense issues, and his willingness to slog through manuals and reports that other senators ignored or parceled out to staff. As a result, Nunn quickly became a kind of bipartisan repository for information and advice on defense matters.

"A lot of the members I was exposed to weren't very bright, weren't hard working and couldn't think for themselves," says former aide Wright Andrews. "Nunn took home volumes of material, and when he came back, he had actually read it."

For Sam Nunn, the relentless reading and the quiet anonymity of his early years in the Senate had less to do with any Machiavellian plan to acquire power than they did with a deeply personal compulsion to learn -- one linked in part to the example of his father's solitary vigil in the family library.

"I guess the most frustrating thing about my daily existence is the lack of opportunity to read as much as I would like, just because there are so many things going on of which I'm not completely aware," he says. "That's just the way I am. I think I'd be that way whether I was in politics or not."

The changes came incrementally but inexorably.

They were not events that Sam Nunn identified as watersheds in his career; they were passages, transitions. His mentors died or were defeated or became infirm. His political base in Georgia broadened and deepened. He ascended the Armed Services Committee's seniority ladder, finally becoming its ranking Democrat. He became a sometime and then a frequent player in the international game of nuclear arms negotiations. And all the while, his life in Washington coalesced -- around his family, his clubs and his friends in the Senate.

Now, 14 years after his arrival in Washington, the traffickers in political wisdom are suddenly talking about him for the vice presidency in 1988, or even the presidency.

He told a reporter recently that he isn't as "immune" to presidential fever as he used to be, but what he meant to say was that he is starting to hear his name on the talk shows and he can't help but think about it from time to time. "I guess nobody was ever talking to me about being a serious candidate. And now people are talking to me about it all the time," he says. "Naturally your mind turns to that."

Yet when his colleagues and his staff take a close look, they see vivid contrasts between the life Sam Nunn leads and the lives of some of his high-profile peers in power: the Senate prayer breakfasts Nunn organized and still attends; the way he rarely goes off the Hill to lunch with lobbyists or constituents, preferring instead to eat in the Senate dining room; his devotion to his weekend golfing foursomes with senators and former senators; the way he heads straight home every night after work.

The sense of "club" that has historically been a part of Senate life is especially important to Sam Nunn, and he rues the ascension of younger senators who seem to him more concerned with parading their ideological feathers than with conducting the nation's business. "You know, people talk about the 'club' and it's usually looked on with some disdain," he says. "But the truth of it is that unless there's at least a modicum of comity over here, and diplomacy, this place won't work."

His critics in the Senate argue that it is precisely Nunn's cautious emphasis on building long-term personal relationships inside the club that now holds him back from unrivaled leadership on the defense issues he knows so well. These critics are mainly liberal Democrats who see Nunn's "moderation," especially now that he is politically safe in Georgia, as a kind of timidity. They argue that Nunn is sometimes afraid to take a stand if he is not certain his Georgia constituents would agree with him. They are also loath to speak about this issue on the record -- like so many others in the Senate, they consider themselves to be "good friends" with Sam Nunn.

One example Nunn's critics cite is the debate over SALT II late in the Carter presidency, when Nunn was identified by both sides as a key "swing" man in the ratification fight. They say Nunn was in a position to make or break the SALT II debate, but was unwilling to assume leadership independent of his elders on the Armed Services Committee.

Nunn's supporters say such criticism is merely sour grapes from left-leaning Democrats who wish Sam Nunn were not such a moderate man. As demonstration that he is willing to take independent and controversial stands, they point to the Panama Canal treaty debate, in which Nunn's support of the accord was crucial to ratification.

"I'm still more conservative than most people in the Democratic Party," Nunn says. "But it's not as wide a gap as it used to be, and I like to think that's because they're coming towards the middle."

The party is moving toward Nunn for political as well as ideological reasons these days. For its national leaders, the most disquieting aspect of Walter Mondale's humiliating defeat was his near-total dearth of support in the South. Nunn has not been cautious about seizing this political opportunity; he has sharply increased his speaking and travel outside of Georgia. With fellow moderates such as former governor Charles S. Robb (D-Va.), Rep. Richard Gephardt (D-Mo.) and Gov. Bruce Babbitt (D-Ariz.), he has also participated in the renegade Democratic Leadership Council, which is trying to coalesce party conservatives by developing new platform ideas.

The lesson Sam Nunn draws from all of this -- from his status as the Democrats' guru on defense, his role in reshaping the agenda of his party, the exhilarating talk about his future -- sounds like political wisdom from a bygone era. If a young senator asked Sam Nunn how to make a name for himself, he would hear about patience and hard work and respect for his elders. He would be told to resist "the compulsion to instruct others in your great knowledge of everything that comes up. People don't buy it after they hear you profess your expertise on about six subjects -- they begin to tune you out. I think that happens to a lot of [senators].

"You know, you can play the media game. Everybody up here knows, supposedly if they've been here for a while, they know how to do it. I would suggest that you not do that. Basically, let that kind of thing come naturally."

And it will come, Nunn knows, even if it takes 14 years.

Sam Nunn's Perry does not resemble Jimmy Carter's Plains. There is a stolid air about its people and its institutions, an ambiance of permanence and dignity and order undisturbed by media-created caricatures of Southern life. There are no Billy Carters here; Nunn's only sibling, an older sister, owns a chain of upscale luggage shops in Atlanta. He has a cousin who still lives in Perry and practices law. His mother, now in her eighties, lives alone in the white, one-story rambler off Main Street that she moved into with Sam Nunn Sr. almost 50 years ago. She is an intelligent and friendly woman who spends her days at church and her evenings filling scrapbooks with pictures, letters and articles about her son's life.

Perry sometimes seems very far away to Sam Nunn these days. Last year, he spent less time in Georgia than ever before. He was in Geneva for several weeks, monitoring the arms talks, and he also traveled to the Soviet Union. It was hard to find time to fly south for the usual rounds of Elks Club speeches and mashed-potato banquets. Nunn worries about losing touch. "People die, people move," he says. "And my new staff people up here don't know the old friends."

So this year he plans to spend a few extra weeks retracing the highways and county roads he drove in his gray Pontiac back in 1972. From time to time he will return to visit with his mother, and stop in at the A-frame house he built for himself in one of the pine forests on the family land. From the interstate, he will drive into Perry on the street renamed Sam Nunn Boulevard, and which the locals call Burger Boulevard, since it is home to nearly every fast food chain in America. He will pass by the tall, ancient Methodist church where his entire high school class attended revival services every morning -- "that was before people knew there was anything unconstitutional about it," he says. And he will stop to talk with some of the dozens of his high school friends who have stayed in Perry all their lives.

Burger Boulevard aside, most things in Sam Nunn's Perry are as they were 40 years ago. The bed he slept in as a boy remains in his room in the back of his mother's house. His portrait, painted when he was a blond and stylish 16, hangs on the mantel in the parlor.

And his father's books rest on their pinewood shelves. If you wandered by that house one evening when Sam Nunn was in town, you might see a light on in the library and the silhouette of the senator erect in an armchair, reading. And you might recall, as Sam Nunn does, a father whose example in Protestant fidelity and intellectual ambition stuck with his son across 50 years and whose shadow followed him to the heights of power in Washington.