NEW YORK - Rudy Giuliani revels in a reputation for being unstoppable - the dauntless prosecutor of mobsters and crooked politicians, “America's Mayor” at the wreckage of the World Trade Center. And now a Republican presidential contender.

But Giuliani does know failure.

He lost his first campaign, a 1989 run for New York mayor, if narrowly and in the face of substantial obstacles.

The loss to Democrat David Dinkins provides an early glimpse into the politician Giuliani is today, and foreshadows some of the issues he deals with as a presidential candidate.

Political observers see a continuum between the pugnacious prosecutor who vowed “to take back our city” from street thugs and corrupt officials in 1989 and the image of tough-minded leadership Giuliani projects on the national stage now.

His campaign skills may be sharper, his political credentials more certain, but “the style is very much the same,” says Lee M. Miringoff, the director of the Marist College Institute for Public Opinion.

“Rudy Giuliani is not shy about drawing a line in the sand.”

Even many New Yorkers may not remember that Giuliani - who recently proclaimed himself “probably one of the four or five best known Americans in the world” - made his political debut as an underdog whose staff made sure to include a tip on how to pronounce “Giuliani” in suggested remarks for then-President Bush.

Not only was Giuliani a first-time candidate - he was a Republican in a city where none had won a mayor's race since the 1960s.

Then, as now, registered Democrats outnumbered Republicans roughly 5-1.

But if Giuliani was an underdog, he wasn't an unknown. He charged into the race on his reputation as a fearsome anti-crime crusader, built during more than five years as U.S. attorney in Manhattan.

Bush called him “America's greatest crime-fighter.”

Even before he moved into the mayor's office, Giuliani impressed people with “a feeling that he's in charge ... you could see it even then,” said veteran New York political consultant David Garth, who worked on Giuliani's successful mayoral bid in 1993.

But along with Giuliani's enduring strengths, some lasting vulnerabilities also emerged in 1989.

He was seen as equivocating on abortion, an issue that hounds him today as he tries to court conservative voters.

The stark racial divide in the 1989 vote foreshadowed tensions in Giuliani's eventual administration - he sometimes declined even to meet with certain black officeholders - that still reverberate.

New York in 1989 was hardly the glossy boomtown of today. The economy was stumbling in the wake of the 1987 stock market crash.

Crime had soared under the scarring influence of crack.

The city counted 1,905 homicides in 1989, while it's expected to log fewer than 500 this year.

Deadly attacks on black men by mobs of whites in Queens' Howard Beach neighborhood in 1986 and Brooklyn's Bensonhurst in 1989 - just three weeks before the primary - had inflamed racial animus and sapped 12-year incumbent Edward Koch's political muscle.

And Dinkins was testing that weak spot by offering New Yorkers a chance to elect their first black mayor.

Giuliani, who trounced cosmetics scion and former U.S. ambassador to Austria Ronald S. Lauder in the Republican primary, presented himself as a City Hall outsider and reformer.

He said Koch was to blame for the city's crime, drugs and corruption, an approach abruptly blunted when Dinkins won the Democratic primary.

Dinkins offered history-making appeal and a message of social healing and unity, seeing a “gorgeous mosaic” in a city others viewed as perilously fragmented.

During much of the campaign, polls gave him double-digit leads over Giuliani.

“People wanted harmony, and people wanted to give David a shot - a person who, they believed, exemplified racial harmony,” says Democratic political consultant George Arzt, then Koch's press secretary.

Still, skirmishes on the campaign trail exposed the fault lines lurking beneath the surface.

The Dinkins camp took heat for hiring black activist Robert “Sonny” Carson, a convicted kidnapper, to organize a voter drive.

A Giuliani ad aimed at Jewish voters that invoked the Rev. Jesse Jackson - unpopular over his famous “Hymietown” remark five years earlier - also heightened tensions.

The campaign's temperature shot up in the final weeks, when Dinkins was beset by questions about his financial dealings. Dinkins denied wrongdoing, but Giuliani leaped to underline the controversy - and his corruption-buster resume.

“A couple of times, it really got a little ugly,” recalls Dinkins campaign manager and later Deputy Mayor Bill Lynch, to whom Dinkins referred calls for comment. But, he says, Dinkins “was a superior candidate. He had a better message. He had a record to run on.”

Dinkins won by less than 3 percentage points, one of the slimmest margins in city history. Exit polls showed as many as 97 percent of black voters and 70 percent of Hispanic voters chose Dinkins, while two-thirds of white voters went with Giuliani.

Dissecting the campaign, some political analysts felt Giuliani had focused too much on exploiting his opponent's liabilities, instead of selling voters on his own assets.

“It was more like a prosecution than a campaign, and it didn't work,” says Quinnipiac University Polling Institute director Maurice “Mickey” Carroll, then a reporter covering the race for Newsday.

But to longtime Giuliani adviser Peter Powers, the ambitious prosecutor succeeded in giving voters a preview of the administration he would eventually run.

“(He) laid the foundation for lowering taxes, restraining spending and cutting crime once he was elected,” said Powers, who managed Giuliani's 1989 race, served as his first deputy mayor and co-chairs his presidential campaign.

Powers also says the race reflected the same sense of focus Giuliani brings to the presidential contest. “He can look down the road and realize that if he is going to run for mayor or for president, that he has to be looking ahead at the kind of city or country he'd like to turn over to the next person,” said Powers, to whom Giuliani's representatives referred requests for comment.

A savvier, better-positioned Giuliani narrowly defeated Dinkins four years later. Giuliani had used the intervening time to sound out a wide range of city experts and interest groups and line up support from prominent Democrats.

He also made his persona looser and more approachable, even appearing in a “Seinfeld” episode involving the mayor's race.

“(Giuliani) was a guy who lost and took the lesson to heart,” Carroll said. “He learned how to win by losing.”