CHICAGO -- Bill Clinton marched down Western Avenue in the city's St. Patrick's Day parade last weekend on his way to what felt like a sure win at the polls. Smartly packaged for the day in a kelly green shamrock tie and boutonniere, surrounded by concentric circles of Secret Service, police on horseback, campaign aides and camera crews, he was clearly the man to watch.

But the average spectator couldn't.

So deeply cocooned was the presidential candidate with the Elvis cool and the made-for-media looks that not a soul on either side of the parade route could see any sign of Mr. Clinton.

If parade-goers balked at their obstructed view -- and they did -- it was hardly the first time voters have complained about not getting a clear picture of the Arkansas governor who last week became the Democrats' presumptive nominee for the U.S. presidency.

Even as voters have cast their ballots his way, they've also wondered about the core of the man -- a man who most outside of Arkansas had never even heard of before last fall (unless they recalled his disastrous nominating speech at the 1988 Democratic convention), a man who's been dogged by scandal, questions of character, ethics and vision, and the dubious moniker "Slick Willie."

"Initially, Bill really captured people's fancy with his vision for change," says Betsey Wright, Mr. Clinton's longtime chief-of-staff in Arkansas. "Then they discovered a candidate who had foibles and made mistakes. It's been a challenge for the campaign to merge that into one person."

Indeed, the "foibles" -- most notably his fuzzy responses to charges of marital infidelity and questions about his draft status during the Vietnam War -- have clouded the picture of this bright, articulate 45-year-old Rhodes scholar and Yale lawyer who's earned a reputation as a leading voice for an activist, reformed government and "opportunity with responsibility."

On the campaign trail, he is a natural. There is the poise and polish, the easy smile, the strapping presence that enters a room and immediately fills it up. Facts and figures and quick answers are always at the ready. He works a mike like a regular Phil Donahue, works a crowd like LBJ at his gregarious best. He asks your name.

He will so stir a Baptist congregation -- shouting "You must believe . . . " until he is red in the face -- that reporters call his road show the "Elvis Redemption Tour." He will engage a working-class audience with his country twang, tell a student group how his seventh-grade daughter faxes him her algebra problems. And then, after a 15-hour campaign day that includes a debate, a parade, five churches, one synagogue and assorted meet-and-greets, the Eveready battery of a candidate will treat a group of journalists to a nightcap of foreign policy talk.

"We haven't had a politician in a long time who's had the fundamental knowledge of public policy that he has," says Baltimore writer Tommy Caplan, Mr. Clinton's college roommate at Georgetown University. "It's surprising to some people. They could find it glib -- but they'd be wrong."

But the public also has glimpsed some rough edges that don't fit so neatly into the package -- outbursts, such as the one television cameras caught last month when Mr. Clinton mistakenly thought the Rev. Jesse L. Jackson had endorsed Iowa Sen. Tom Harkin, that suggest why the governor once gave his chief-of-staff a set of earplugs.

"I've seen it a lot of times," Ms. Wright says of her former boss' anger, which she believes is linked to bad allergies that have long plagued the candidate. "He only explodes like that when his sinuses are unbearably painful."

But perhaps the greatest question about Mr. Clinton -- a brilliant student of U.S. politics who, at age 10, sat spellbound in front of a TV watching the Democratic National Convention and decided he wanted to play that game -- is one of his honesty and commitment.

Is he the devoted public servant driven by strong, personal beliefs and a grounded moral compass -- the Bill Clinton who drove the family Buick into riot-torn Washington the day after Martin Luther King Jr. was killed to get food and supplies to displaced blacks?

Or is he a political chameleon driven by sheer ambition and the direction of the wind -- the Bill Clinton who promised Arkansans in 1990 that he would serve out a complete four-year term as governor if they voted for him and is now on a carefully plotted journey to Washington?

"If he has an obsession, it's to make a difference in this world," says an ally, Ms. Wright.

But J. Bill Becker, president of the Arkansas AFL-CIO, gives this succinct answer to a question about the governor's guiding principle: "Winning."

Mr. Becker, who's known Mr. Clinton for 20 years and counts him a friend, nonetheless rattles off examples of broken promises and cagey answers from his fellow Arkansan. In trying to get an increased sales tax through the Legislature in 1983, the governor sought support from a coalition of labor unions and other groups, says Mr. Becker, and promised to exempt food from the sales tax in exchange for the coalition's backing of his bill.

"We made a deal. We helped him, but he didn't help us," says the longtime union chief. "He reneged on his promise."

But Mr. Clinton has said repeatedly that he made no such promise and that the coalition misinterpreted the arrangement.

"He always has an answer for what he does, and it always sounds credible," says Mr. Becker.

Such critics point to Mr. Clinton's recent telling of a pivotal moment in his life -- a confrontation, at age 14, with his alcoholic, sometimes violent stepfather -- and his somewhat different recounting of the episode three decades ago. In interviews along the campaign trail, Mr. Clinton has said he barged into his parents' bedroom, warned Roger Clinton, who died in 1968, never again to physically abuse his mother, Virginia, and effectively put an end to the violence.

But in testimony given in the couple's 1962 divorce proceedings, 15-year-old Bill Clinton said that the abuse had continued and that he, in fact, had been threatened by the elder Clinton in their last confrontation.

Mr. Clinton, whose natural father was killed in a car accident three months before he was born, has explained any discrepancy by saying that his stepfather's violence did cease, but only as long as the teen-age son was in the home.

Critics see the varying versions as evidence of the five-term governor's well-honed ability to finesse any edges, a trait they believe dovetails with what they call his weather vane politics.

"He tends to be all things to all men," says Paul Greenberg, editor of the Pine Bluff (Ark.) Commercial and author of the "Slick Willie" sobriquet. "I've been trying to get a handle on him since 1976, and he's slipped out of my grasp. There might not be anything there to grasp in terms of simple principle."

But the candidate's friends -- and they are a broad and often influential network referred to in campaign lingo as FOBs (Friends Of Bill's) -- are quick to point out the principles that they see as Mr. Clinton's political rudder.

"The guy is angry about injustice," says campaign aide and fellow Oxford student Saul Benjamin. "He grew up with it; I don't think he ever got it out of his bones."

Indeed, Mr. Clinton's message of "reaching across racial lines" and "becoming one again" -- emboldened by childhood memories of a racially divided South -- resonates with minority audiences that have become a part of the broad coalition he's built.

Carolyn Y. Staley, next-door neighbor to teen-aged Billy Clinton in Hot Springs, Ark., traces her friend's civil rights commitment .. to the kitchen table of the new home the Clintons moved into in the early '60s, a display home built to showcase the latest in "future living" technology.

With Ray Charles or Dave Brubeck on the record player, Bill, Carolyn and other friends would sit around a pot of coffee on Saturday mornings, as Bill's mother, a nurse-anesthetist, would engage the teen-agers in conversation about some inequity or injustice she'd just witnessed or heard about.

"We would try to come to a conclusion about what the essence of the wrong was and what was the solution," recalls Ms. Staley. "All that time was like an incubator for Bill."

It is a thread that seems woven throughout his life. Sailing for Oxford aboard the USS United States in 1968, the young scholar not only charmed his fellow students playing James Brown's "I Feel Good" on his sax, he forged ties with some of them -- including Washington lawyer Thomas Williamson Jr., the only black on the boat -- that continue to this day.

"That first day on the boat, he came up to me, 'Ha, Ah'm Bill Clinton,' " recalls Mr. Williamson. "Initially, I was rather wary of him. I figured he just wanted to validate himself by associating with me on a token basis. But it became very evident he was just as outraged as I had been about [racial injustices]."

Such outrage, along with a dedication to education reform, have guided him through Arkansas politics, supporters says. But friends and foes alike agree Mr. Clinton's 1980 gubernatorial defeat -- after a single term in which the young firebrand championed controversial issues, brought in outsiders to run agencies and, as he has said, tried to do too much too soon -- forever changed the way he played the game.

"It was a deeply disorienting event for him," says Mr. Benjamin, the campaign aide. "He was used to winning."

The loss was so devastating, says Ms. Wright, who moved to Arkansas soon after to head his re-election campaign, that he spent a year praying and asking voters where he went wrong. "Not because he didn't get it, but because he wanted it absorbed in every cell of his body and brain."

Some see the two years leading up to his re-election as the political maturing of Bill Clinton, when he learned the value of pragmatic leadership and peace-making. He and his lawyer wife, Hillary Rodham, who took her husband's name after voters made it clear they didn't approve of a first lady with her own, decided they needed to focus on one or two issues and made education and the economy their priorities.

But others say the defeat drove the passion from the astute politician.

"He set out never again to offend a single voter," says Mr. Greenberg, the Arkansas newspaper editor. "I can't imagine him now losing some political viability on behalf of a principle."

Perhaps the greatest turning point of all for Bill Clinton was one he did not witness: the blown tire that resulted in the death of a handsome, outgoing traveling salesman named William Jefferson Blythe III -- his father -- shortly before he was born.

"Bill always said he felt a sense of urgency of having to live life for both of them," says Mr. Caplan, his former roommate. "He has a sense of having an abbreviated time span."

Right from the start, William Jefferson Blythe IV, as the leather-bound Bible that sat in the Clinton dining room is inscribed, was an unabashed achiever.

Not his class at Georgetown University, not even his Sunday school class at Park Place Baptist Church escaped having the young, studious man elected as its president.

Some say the political switch was tripped as early as 1963, when 16-year-old Bill Clinton, who took his stepfather's last name in high school, spent a week in Washington's power corridors through Boy's Nation, an American Legion-sponsored program. In the White House Rose Garden, he shook hands with John F. Kennedy. In the Capitol building, he rode elevators with the likes of Hubert H. Humphrey.

"We didn't feel there was anything except time that separated us from being in those halls ourselves," says Ms. Staley,who was in the girl's program. "When Bill came back from Boy's Nation, he had turned the corner -- although there had never been any real question."

Indeed, it appears he's been preparing for this day ever since that heady summer of '63. But his political lessons haven't only come from his wins and losses in the state where his grandfather ran a grocery store, his cousin a watermelon stand, his uncle a Buick dealership.

With the same vigor he brought to his studies at Georgetown, Oxford and Yale, he's examined every recent race for the presidency and can give you details -- percentages candidates received, where they did well, where they stumbled. "He has carefully lived each one," Ms. Staley says.

Now his own campaign may be a model. With a well-built, well-heeled organization that got to work early, he has so far survived the probes and attacks many strategists believed would prove fatal. It is, perhaps, no accident, nor blind luck.

As early as last spring, the politician could be heard setting the pTC stage for those "foibles" he knew would surface in his pursuit of the nation's top office. He told a state Democratic convention in Louisiana last May: "The American people don't want a perfect person."

It is a theme he repeats again and again these days -- at churches, at schools, at shopping malls. He is not perfect. "There will be some days when you'll think I slipped a gear," the engaging man on the political escalator told a crowd in Illinois before stepping off there a winner. "But I'll tell you one thing, we'll be going in the right direction."