Jack Kemp, U.S. representative, is talking low. "What I like about quarterbacking is you control the situation. You go in a huddle, you call a play. If it works, you're in. If it doesn't, you're out." His thumb jerks skyward, like an umpire's. Then, in the manner of old athletes and Southern fraternity boys, he nudges you - an affectionate tuck.

There is a certain aura. You see it in his walk. You see it in his dress and great shock of Kennedy-like hair. Most of all you see it in his smile, which is not so much a smile as a secret grin, an insider's wink.

Jackie Kemp used to play pro football. As a quarterback, he had neither the native skills of Johnny Unitas nor the public relations of Joe Namath. He was a canny, dogged competitor who could heave the ball 70 yard (to Elbert "Golden Wheels" Dubenion) and who twice led the Buffalo Bills to American Football League championships. In all, he survived 13 autumns in a game where the average quarterback doesn't last five. His jersey now hangs in the Pro Football Hall of Fame.

Today No. 15 is starring for the GOP. There are other stars too, but they haven't dimmed the 42-year-old Kemp's any. There are lots of signs of his sudden success: In the phone that rings off the hook of late, the calls coming in from New York moneymen, from Republican party powers, from national magazines, which want to snap pictures and talk about the tax revolt, especially after the Proposition 13 tidal wave. For five years, taxes have been Jack Kemp's issue.

In his manic travel schedule. Fund-raisers, state conventions, local Republican campaigns. Talk show appearances. The ceaseless trips back home to the 38th - more handshakes with Lackawana steelworkers.

"Is he on 'Today' tomorrow, or 'Tommorrow' today?" and aide recently wondered.

In April, the Republicans held a much-publicized "Tidewater Conference" in Easton, Md. Hugh Sidey of Time magazine wrote there was a "Kennedy-like stir" when Kemp strode in.

A couple of weeks ago, in a Buffalo union hall, the congressman had several hundred elevator constructors of Local 14 standing on their chairs and stomping for him. This, from a conservative Republican with one of the lowest AFL-CIO vote ratings in Congress.

Despite all of this, Jack Kemp insists he isn't running for president. That would sound overraw with ambition. All he will say publicly is that he's running for the Senate in 1980, for the seat of New York Sen. Jacob Javits. And on this, he waters the bets. He will "reevaluate," he says, in the event Javits decides to run.

"Let me say this," says Jack Kemp. "I'm running for the Senate so I can get in a better position to implement my ideas. For me to think of anything beyond that would be . . . presumptious."

Pause. "Besides, getting to the Senate will be tough enough. I'm an upstate candidate in a downstate state."

He is smiling. The Laffer Curve

He looks pinstripe-perfect. His shirt, with a gold collar pin, hasn't a crease.The tie is a club, the watchband black suede. The body is tan and muscular. On the thick right hand, which chops and jabs continually, is a large championship ring. Only the voice suggests a flaw. It is thin and scratchy. Jack Kemp has been talking a lot.

He is taking lunch in the Members' Dining Room. The maitre d' seats him immediately, and when the waiter brings him a bottle of Coke, the drink is already steaming over ice. "I poured it for you, Mr. Kemp," he says. "Didn't want it to be warm."

"Hey, Kemp," calls a woman from the next table. "I see you everywhere. You were on Cronkite the other night."

"Now. Now. Now. I'm ubiquitous."

Someone else comes over to shake. "Hey," he waves to a man exiting. "See you in committee." It goes like this. He is only toying with his grilled cheese: Jack Kemp has a small growing roll on his stomach.

His attention focuses: "I make no bones about it. When I was 6 years old, all I wanted was to be a professional football player. I went through college to play pro football. But the craziest thing: After I got there and proved myself, it wasn't enough. I had to do something else."

And then:

"You only had three seconds to make up your mind. I remember this one time we were playing the Eagles at home. We were losing bad and the Buffalo fans were on me unmercifully. When I came back on the field after halftime, the place erupted. On the first play I threw the bomb for the touchdown. Something like that does things to your head. You learn quickly about success."

Jack Kemp hasn't gotten here, to a star of his party, on just good looks and tasseled loafers - or old football laurels. Jack Kemp has an issue, a horse he's ridden relentlessly for five years and which only now is taking off across the country like some unstoppable Secretariat. The issue is taxes, and Proposition 13's recent landslide in California is only the loudest of the evidence. (Kemp was a speechmaker there.)

Kemp wants to cut taxes across the board. Immediately and drastically. He is coauthor - with Republic Sen. William Roth of Delaware - of the Tax Reduction Act of 1977, a bill that would reduce all individual tax rates by 33 percent in the next three years. The bill has 167 cosponsors in the Congress and an endorsement from a party that has always worried that about "fiscal responsibility."

"This issue goes beyond conservative-liberal or Republican-Democratic dialogues," Kemp says. "It even goes beyond taxes. It has to do with putting rungs back on that ladder, with removing barriers between your efforts and your rewards. The real issue is government promoting a climate for increase and growth. It's about hope and . . . and OPPORTUNITY. Yeah, opportunity."

At the heart of the Kemp theories is something called the Laffer Curve, a neoclassic economic explanation of how the world works, courtesy of a current professor at the University of Southern California named Arthur Laffer. Laffer's curve tries to show that while a cut in the tax rate may decrease revenues in the short run, it will actually create a bigger GNP in the long run. The reason: increased incentive to work.

Kemp has taken up the Laffer Curve like breakfast cereal. He's forever drawing it on napkins and the backs of envelopes for would-be converts. And he's not alone: Thinkers like Irving Kristol, American Enterprise Institute scholar (and coeditor of Publi Interest), and Jude Wanninski, until recently editorialist for The Wall Street Journal, have come into the fold too.

Kemp and Wanniski and Kristol are often in touch these days. "Irving's the godfather of this movement," Kemp says. A couple of weeks ago, Kristol put together a quiet New York dinner for Kemp. Attending: Len Garment, Frank Gifford, Pete Rozelle, Wall Street money types, Lindsay types, Rockefeller types. "I don't want to say they all walked away as card-carrying Jack Kemp supporters . . ." says Kemp.

To some, the whole notion of an exquarterback as sudden economic salvationist and presidential possibility is as much a laugher as the Laffer Curve. Robert Brandon is director of the Nader-associated Tax Reform Research Group, a lobby that believes the way to solve the tax dilemna is to get rid of loopholes and subsidies. He thinks the Laffer Curve is "pretty much garbage" and that its mouth piece Kemp "gets into trouble once you're beyond the slogans. As soon as you start pushing him on the theories, he panics." He adds: "I'd hate to see the responsibility for the cure of America's economy in the hands of Jack Kemp."

"I've got to get together with those guys," says Kemp guilelessly.

In truth, Kemp does seem at ease answering the first question: on the follow-up he seems sometimes not so sure, confused. He's aware people have snickered over his intellectual capacities, have called him a Jackie-one-note. He thinks it mostly has to do with people's images of jocks. The past cuts both ways, he agrees.

"Look, I haven't been trained in the modern school of economics. But I understand incentive. I know wny those guys go into Bethlehem Steel with their lunch pails every morning: for income after taxes. And the problem is that income is being taxed away. People are thinking on the margin."

He tacks on: "I may not totally be on the right track. But I'm not far off."

Kemp is a natural at delivering political bell-ringers. It takes him about 13 seconds to get warmed up. Sometimes his tongue can't keep up. "Government used to be an umpire," he fairly shouts. "Now you get the feeling it's the other team."

Or: "I think we should expand the franchise. I think the Republican Party has got to be more democratic. With a small d. A small d."

Tell him his gospel sounds populist, and he will say, in a big, stagey whisper: "I think this party needs a little populism. The people know what's right, and they know instinctively when something's wrong. The disdain in some people for 'the people'."

John Kennedy's name is often on his lips. No partisanship here. His 1962-63 tax cuts "did more to stimulate the economy and restore incentive than any other post-war measure," Kemp thinks. (Critics would say it was really Vietnam that did the stimulating.) In fact, Jack French Kemp has been heard to proclaim on podiums, with appropriate gestures: "We're got to get this economy moving again." At least, say the detractors, his initials are right: JFK.

"I had a crewcut till I was 36," says Kemp. "I am greatly amused by all this talk about my hair." The All-American Look

Jack Kemp's office. A trophy room, of sorts. Quotes from Vince Lombardi. Pictures of him in uniform, standing with O. J. Simpson, getting squashed by Ernie Ladd. Over the years in football, Kemp sustained two broken ankles, a broken knee, two broken shoulders, 11 concussions, various broken fingers. "So I decided all I was good for was politics." That always gets a laugh on the banquet circuit.

Kemp grew up in Los Angeles, the son of a small businessman. His dad was the giant of his life, he says. He has three brothers, all of whom played football and today are successful businessmen. "I'm the black sheep." At Occidental College, Jackie took physed.

There are also pictures of his all-American-looking family: two boys, two girls, wife Joanne whom he met in college. Kemp's oldest son attends Dartmouth. He's a pitcher on the baseball team. "Pitching is quarterbacking," dad says, flashing the insider's grin. His other kids are into tennis and soccer. The whole family skis.

Kemp says he avoids the cocktail circuit. "When I'm in town I'm home every night by 7:30, 8 o'clock. I think one of the sad things about this business is guys who never see their kids grow up." He admits, though, there have been some tough times of late. On the weekend his son came home from college, Kemp was jetting around the country for the party. He got back in Washington at 9 a.m. Monday.

The Kemps have a home in Bethesda. Also one in Hamburg, N.Y. When he's not on the road, Kemp says he likes to curl up with an economics tome. Nam's like Walter Heller and John Maynard Keynes come easily to his lips.

Not long ago the [WORD ILLEGIBLE]major was awarded an honorary doctorate. When he got home he dressed up in his academic garb for his youngest son. "He told me the only Dr. he knew was 'Dr. J.'"

A secretary comes in now to say a man and his son are out in the reception area and would like a picture signed. "Are they from Buffalo?" he asks. "Send them in."

The kid's name is Patrick. The cat has his tongue. "What's your favorite sport?" demands the congressman.


"Hockey? That's not a sport. There's no quarterback in hockey." He cuffs the kid and gets a grin.

After they are gone, Kemp says: "One of the things that pleases me most is I'm doing all this from Buffalo. Not from Southern California, you understand, but from depressed old Buffalo. Hell, my district must be the most ethnic district in the country. We've got Italians. We've got Germans. We've got Polish. We've got Irish. These people feel they're drowning. My state is the Great Britain of the North American continent - the most heavily taxed in the nation. People in Buffalo can't understand why their picture lands on the front page of The Washington Post after a snowstorm. Why not Cleveland?"

Pause. "People up there always tell you how they fell, though: 'You're okay in politics, Kemp. I liked Lamonica better in football'." (Kemp got elected for the fourth time with 78.1 percent of the vote.)

A scintilla of nostalgia leaks out. "I saw a film clip awhile ago of me throwing the ball and Gladys Knight singing in the background. It hit me hard . . . I'd never throw a football again while 70,000 people are cheering." A couple weeks ago, he had lunch with Nick Buonoconti, feared middle linebacker for Miami, now a successful lawyer. "We must have played against each other three times a season for 10 years. It was a chess game."

He is asked about ego, and how much that - in addition to his prefervid belief in tax reductions - drives Jack Kemp. A grin. "Could it be otherwise?"

He senses what is coming. "Look: If the only way I thought I could lower the taxes for the people of Buffalo was to run for president, then maybe I would run for president in 1980. But you appreciate I'm saying that jocularly."

He leaves it hanging there, tempetingly, in the bright summer afternoon.