The Republican candidate hunts boar, cracks jokes in Latin, traces his lineage to a signer of the Declaration of Independence, and grew up on an estate with a 130-acre duck pond. The Democrat hails from a clipper-ship dynasty, can do barrel rolls in a stunt plane, married a ketchup heiress worth $675 million, and was trampled by a bull in Pamplona once, then got up and chased the bull.

They are two uncommon men -- Republican William Floyd Weld and Democrat John Forbes Kerry -- trying to appeal to the common man. Two millionaire blue bloods and wonder-grads of Harvard and Yale, respectively, are begging for support from the scuffed-shoe middle class in one of the country's most fiercely contested Senate races. Five weeks from Election Day, polls say Massachusetts voters are evenly torn between the two suitors.

Both are smart, charming and handsome and fancy themselves presidential stock. Both are popular incumbents with strong records: Weld, 51, is a second-term governor, an affable goofball pol with pink cheeks and hair the color of Cheez Doodles. Last month, at a signing ceremony for environmental legislation, Weld, true to form, dove into the Charles River fully clothed. Kerry, 52, is a two-term senator, an intense, serious legislator who looks like Dudley Do-Right's nerve-racked brother. A Vietnam hero who turned against the war, he still stalks through life -- and Congress -- with the mixed appeal of an avenger.

The sheer spectacle of these two candidates, who both hover around 6 feet 3, stirred the audience at a recent debate in Worcester. It was the fifth of eight hour-long philosophical jousts.

"They're both giants," said the Rev. Thomas Sullivan, a Boston priest and Kerry supporter.

"Both have more money than we'll ever see in our lives," said Paul Kosky, a Framingham teacher who's voting for Weld.

There's no resentment at the mention of such wealth. This is Massachusetts -- Kennedy country -- where people expect, and enjoy, aristocrats, intellectuals and eccentrics on their ballots.

"Neither one of us has exactly lived hand-to-mouth," quips Weld, in an interview. "My staff laughs at me when I say this -- but when I want to know what the man on the street thinks, I ask myself: What do I think?' "

When Weld declared his candidacy, he explained his decision in a Boston Globe Op-Ed piece: "Working families toil for every dollar, struggling to pay the mortgage, put groceries on the table, keep a car on the road and educate the kids. I want to go to Washington to represent them by fighting for lower taxes."

But Kerry insists that he is the true choice for the middle class. "His tax cuts go to wealthy people and corporations. My tax cuts go to working people," Kerry says. "This man is a libertarian conservative trying to masquerade as a friend of the working people . . . and I'm going to sound the midnight alarm bell and he's going to turn into a pumpkin."

So far, there has been a genuine contest of ideas: a classic Republican vs. Democrat clash over the role of government in the economy. (On social issues, they share more common ground; both are strong supporters of abortion rights and gay rights, for example.) Weld, a social liberal and fiscal conservative, is wielding the crime-welfare-taxes trident. Kerry is sounding traditional Democratic themes of education, health care and tax fairness. He voted for increases in the minimum wage and college loans.

But as Nov. 5 approaches, the taste of the race is growing bitter. Weld is trying to paint Kerry as a big-spending liberal who is soft on crime and voted for the welfare bill only because of an election year conversion. Kerry calls the election a "battle between a social conscience and the policy of abandonment" and is trying to link Weld with House Speaker Newt Gingrich (R-Ga.). During the Worcester debate, Kerry charged, "You talk out of both sides of your mouth more than Budweiser frogs."

In an interview afterward, he said Weld kind of looked like a frog.

In another world -- say the yacht club -- you might imagine these two ideological opponents being chums. They have more in common with each other than with most of the state's electorate. At Yale, in fact, Kerry's best friend, David Thorne, heard from his friends at Harvard about "a bright, politically ambitious good-time Charlie," a classmate named Bill Weld. "Weld was part of a preppy group my friends were part of," recalls Thorne.

Today, the candidates are desperate to distance themselves from each other. Kerry's rhetorical refrain has been "Governor, the difference between us is . . ."

And yet outside the policy arena, they speak a common language. "We might have enjoyed fly-fishing," Kerry muses, sitting in his Senate office. "I invited him fishing a year and a half ago down the coast." He doesn't specify the town, although Kerry's family owns a string of private islands southwest of Woods Hole where he windsurfs and sails. Weld declined Kerry's invitation, Kerry says: "He was too busy -- plotting his run against me, probably."

Plotting like a gentleman, to be sure. Weld and Kerry agreed to an unprecedented spending cap in their Senate race, limiting each campaign to no more than $6.9 million. After months of fruitless haggling and suspicion between their staffs, the candidates decided to meet face to face. Weld visited Kerry at his $2 million, five-story brick town house on Boston's historic Louisburg Square.

Weld recalls, "He said, Bill, I give you my word as a gentleman' " not to exceed the spending cap.

Weld says he closed the deal warning: If you break the agreement, I'll make it known among the ski set at your retreat in Sun Valley. And if I break the deal, you can bad-mouth me to my fishing pals at my club in Keene Valley. Crossing Party Lines

Confused? Here's a quick way to tell the candidates apart:

The Republican is the guy who married the great-granddaughter of Theodore Roosevelt. A sometime Democrat, Susan Roosevelt Weld voted for Michael Dukakis in the 1988 presidential election. She opposes her husband's tax policies, favoring a 70 percent tax bracket for the wealthy, and disagrees with his support of the death penalty.

"It makes the blood run cold," she says, speaking of how whites and blacks are sentenced differently. "I've read all those studies how the same crime by a black person ends up on death row. That's a fundamental injustice."

The Democrat is the guy who married the widow of a Republican senator. Teresa Heinz cannot vote for her husband because she is still registered in Pennsylvania, where the late John Heinz served as a senator.

"I'm a Republican," Heinz says. She married Kerry, who was previously divorced, last year. "But the kind of Republican my husband, Jack Heinz, was. I'm not the kind of Republican I see on the Hill -- they've lost their hearts."

Weld's and Kerry's choice of wives, and their wives' outspokenness, reflect an independent, principled streak in both men.

After winning a Bronze Star, a Silver Star and three Purple Hearts in the Navy in Vietnam, Kerry returned to lead Vietnam Veterans Against the War.

As a student at Yale, he admired John F. Kennedy and wanted to model his life after the president. He even dated Jacqueline Kennedy's half sister for a while.

"When John Kerry graduated from Yale he went to Vietnam to be Camelot," but he felt betrayed by the government, says Tom Vallely, a longtime Kerry friend who is a Harvard administrator. The experience changed him, friends say; it made him skeptical of authority.

Weld, a former U.S. attorney and chief of the criminal division in the Justice Department, has had his maverick moments, too. He quit his Justice post in 1988, charging that Attorney General Ed Meese had abused his power. And during the Whitewater hearings, Weld snubbed his Republican colleagues and offered to serve as a character witness for Hillary Rodham Clinton. "I regard her as a person of integrity and I know her very well," Weld said on the "Imus in the Morning" radio show. "So in no way I see her at the center of a web of coverup."

The quirkiness and individuality of these men have worked both for and against them in the Senate race. Weld's libertarian "against government in your pocket, against government in your bedroom" stance has won him votes in the past in the hipper precincts of Cambridge and Brookline, while appealing to Boston's old money, too.

Weld was reelected governor in 1994 with 71 percent of the vote in a state that is only 13 percent Republican.

"On social issues Weld is very liberal -- he's to the left of me," says former Massachusetts governor Dukakis. "That softens the very conservative economic position."

Weld's broad-appeal pitch undermines him among the right, however. Now his poll numbers are being dragged down by a third candidate, the Conservative Party's Susan Gallagher.

Weld says he wants to run for senator because "I think the federal government is too damn big. I want to get a throttle hold on it." He has said, "We've succeeded in changing the political culture of Massachusetts. Now it's time to change the political culture of Washington, D.C."

And his good-humored, easygoing manner has helped him sell his program. He jokes that his 13-year-old daughter supports Kerry: "She doesn't want to leave her stuffed-animal collection in Cambridge."

But such affability has contributed to his reputation as a political dilettante who is bored easily. Some say he is running simply for the sport of it. Weld himself jokes that he fits the profile for general relief: male, slightly overweight, over 45, with no stable work history. "This is the longest I've ever held a job," he says happily. Before being governor, his longest unbroken tenure (in government or as a lawyer) was 4 1/2 years. "I'm hanging on," he says.

Kerry has his own set of circumstances to keep him from pulling ahead of Weld. Even though he is the incumbent and represents a state where President Clinton leads Republican opponent, Bob Dole, 62 percent to 24 percent, he is in trouble in traditional Democratic blue-collar areas. This is true partly because with Ted Kennedy in Washington, it is hard to be anything else than that other senator from Massachusetts. It is also true partly because governors often are able to deliver more specific goodies than senators.

But part of Kerry's problem is that he has focused on relatively arcane issues.

"I played a critical role on the oceans subcommittee," Kerry says proudly.

But does anyone in Springfield care?

"Kerry has a strong record, but in areas like foreign policy that don't command breakfast banter," says Richard Gureghian, a Democratic media consultant who worked on Kennedy's Senate campaign in 1994. "People don't talk about what's going on in Zaire in a Dorchester diner -- but they do talk about welfare."

Also, Kerry has what his aides call "an intensity problem." His awkwardness comes off as imperiousness, his zeal as piousness. His face sometimes looks as if there's an invisible drawstring at the center, pulling his features tight.

The Kerry campaign frames the race as a contest of policies, not personalities, and hopes voters view the election as a partisan battle to return control of the Senate to the Democrats. "It's a job in the U.S. Senate. We're not running for roast master," says Michael Meehan, Kerry's communications director. "It's not about who's going to be the funniest guy in the barroom on Friday night."

"If he seems a bit intense at times -- and I know, he does," Teresa Heinz told a crowd at a recent rally, "it's because of what he has seen" in Vietnam.

She says the war is at the heart of Kerry's identity.

She wakes up sometimes in the night to a husband still in the grip of a battlefield nightmare.

"Get down!" Kerry shouts. "I got the women and the children! Get down, get down!"

Kerry flies out of bed and hits himself, she says, or crashes into a wall. The dreams come less often now. But Heinz recalls the moment she first heard him thrashing around in his sleep.

She was visiting Kerry in Massachusetts, staying in the room next to his, with one of Kerry's two daughters. "I was asleep and all of a sudden it sounded like the house was being torn down," Heinz says. "I stood quietly in the dark, terrified."

Kerry's daughter was unperturbed. "Oh, Dad's just beginning to relax. When Dad relaxes, he has nightmares." Laboring Men

The debate in the Worcester auditorium is sharp and hot. Kerry repeatedly mops his brow. Weld's face shines strawberry pink through layers of pancake makeup. Each struggles to show how his opponent is out of touch with working men and women.

"The difference between us, governor," Kerry says: "I want to put cops on the street and you want to take them to fund-raisers with you around the country."

Later Weld fires back, "Senator, if your name was John Six-Pack instead of John Forbes Kerry and you had to gas up your motorcycle, your speedboat and your airplane every weekend as well as your car, you would have thought twice before you proposed raising the gas tax by 50 cents a gallon."

Afterward, the instant analysts call it a draw; the candidates are right back where they started -- in a dead heat. They file offstage with their wives.

As the auditorium empties, the smell of sweat lingers onstage, the smell of two working men who want the same job. CAPTION: Making a point: Massachusetts Gov. William Weld, foreground, uses body language in a Worcester debate with his U.S. Senate opponent, Democratic incumbent John Kerry. CAPTION: Aristocrats who have more in common with each other than with most Massachusetts voters: Democratic Sen. John Kerry, above, and Republican Gov. William Weld, below, greeting supporters before a debate in Worcester.