BOSTON -- Mayor Raymond L. Flynn likes to go to fires. So, few were surprised last July when Flynn, who was playing basketball at a nearby public-housing project, rushed to the scene of a burning house, kicked his way in and rescued an elderly man.

If these heroics produced yet another dollop of favorable publicity for Flynn, that too has become utterly routine for the 48-year-old Democrat, whose rolled-up-sleeves approach to government has him riding so high in the polls that many people here are unaware that there is a mayoral election Tuesday.

In a remarkable twist of fate, Flynn, an all-America basketball star at Providence College, has become even more popular in the impoverished black precinct of Roxbury than in his native South Boston, a white ethnic bastion where antibusing fervor took on a racist tinge in the 1970s. Flynn was a leader of that antibusing movement and was distrusted for years by most black leaders.

But today, four years after defeating a black candidate in an election decided along racial lines, Flynn is widely credited with easing racial tension in this battle-scarred city. From his first days in office, when he delivered a check to the widow of a black man killed by police, to his recent march alongside civil rights activists in Georgia, Flynn has successfully preached racial harmony.

It has been quite a metamorphosis for an Irish politician who built his reputation on trying to keep black children out of white schools. Perhaps only the first Boston mayor elected from "Southie," the son of a longshoreman and a cleaning woman, could have pulled it off.

So pervasive is Flynn's grip on the electorate -- he received a 78 percent favorable rating in a recent Boston Globe poll -- that some detractors grumble about his Teflon image, saying that he somehow escapes the blame for declining schools, paralyzed traffic and soaring housing costs.

City Council member Joseph M. Tierney, a Democrat who is Flynn's main opponent in Tuesday's first-round nonpartisan election, calls the mayor "a TV wonder" who has "been on television more than all the anchorpeople combined in Boston."

"People are sick of him chasing the television cameras and the fire engines," Tierney said. "There has been an enormous disparity between the promises and the performance."

Flynn, who often races to disaster sites as he jogs around Boston's streets in a sweatshirt, makes no apologies for his unorthodox style.

"I just can't imagine how anyone could run a government by being stuck in their office all day long," Flynn said in an interview.

"I've been doing this for 17 years," said Flynn, a former state legislator and City Council member. "Attending those neighborhood meetings with five people, six people, 15 people. There are no TV cameras out there for those meetings.

"When I ran four years ago, I had no money, I had no media, I had no political support, I had no business support," Flynn said. "I had to go out and do it the old-fashioned way."

But Flynn also knows a few things about handling the news media. "He's a guy who over the years has learned to think like a reporter," said Steven Pearlstine, senior editor at Inc. magazine and a former editor of the Boston Observer. "He knows what a slow news day is. He has an event-oriented way of looking at things."

Other factors have worked to Flynn's advantage. He follows the 16-year reign of Kevin White (D), whose autocratic style and legacy of corrupt government is not missed by most voters. And a booming regional economy has generated thousands of new jobs here and allowed Boston to run a budget surplus for the first time in a dozen years.

By all accounts, though, Flynn's defusing of the race issue has been his most important achievement.

He has boosted the number of minorities hired for city jobs and named blacks to such key posts as city auditor and treasurer. And since he began denouncing racial violence in 1983, the number of race-related complaints reported to police has dropped significantly.

When court-ordered school busing began here in 1974, however, Flynn played a far different role. While black youngsters were being pelted with stones in front of South Boston High School and black adults were being beaten, Flynn introduced a bill in the state legislature to repeal the compulsory education law and make it legal for white parents to keep their children home from school.

Flynn doesn't like to dwell on that era and will not talk about how his views on race changed. He says only that he sensed it was time for a new approach.

"I had seen the city be divided, seen what it did to people," he said. "It brought out the worst in the city. People were really tired of that kind of polarization."

Once the busing furor subsided, political observers began talking about a new Ray Flynn. In 1979, he rescued a young black man being chased across Boston Common by a gang of bottle-throwing white youths. In 1980, he was the only white official to attend the funeral of a black teen-ager fatally shot by police after stealing a car.

After he became mayor, Flynn's peace-making efforts initially produced a backlash in some quarters, a feeling that "the mayor was bending over backwards for the blacks and not for whites," he said.

But his new approach did not go unnoticed in black precincts, some of which produced only a handful of votes for him in 1983. On a recent Saturday, shoppers interviewed at a discount store in a black neighborhood had only kind words for Flynn.

"It doesn't matter to him what color you are," said Vashnie Dobson, who praised Flynn for appearing at fires and other trouble spots.

Bruce Bolling, Boston's first black City Council president and an occasional critic of Flynn's policies, said the mayor "made it very clear early on that he was not going to take any nonsense when it came to outbursts of racial violence. It was the first time that a white elected leader was so definitive and clear about that."

Still, some blacks remain skeptical. "When blacks were being stoned in South Boston, the mayor was part of that movement," said Roxbury activist Kenneth H. Wade.

Other critics of Flynn's administration say it has been short on substantive results. For example, Tierney, 46, talks about the high dropout rate in city schools, the lack of facilities for heroin addicts and the rapid downtown development that has choked traffic here.

Although these could be hot political issues, Tierney's sweeping solutions -- abolishing the local school board, for example -- have fired no one's imagination.

Tuesday's preliminary election, which will lead to a November runoff, has been so low-key as to be nearly invisible. At a recent political forum at a senior citizens' project, candidates and reporters outnumbered the voters.

While Flynn has amassed a $1 million war chest, Tierney, a 16-year veteran of the City Council, has raised only a tenth of that. Tierney's shoestring campaign, managed by a former YMCA director, can afford to advertise only on ethnic radio stations.

By contrast, Flynn raised so much money from developers, who once viewed him warily, that he ran into controversy and eventually returned $46,000 to contractors with pending city business.

All this is a far cry from the 1983 race, when Flynn went to political consultant Michael Goldman with $4,000 in cash and asked him to run his campaign. "I told him to take that money and take his family to Disneyland because he wasn't going to win," Goldman recalled.

But Flynn, campaigning with his wife and six children from an aging stationwagon, stunned the experts by topping a field of nine candidates, then defeating former state representative Melvin H. King in a runoff. Blacks, who make up one-quarter of this city of 600,000, voted overwhelmingly for King.

Flynn ran as a populist, promising to turn City Hall's attention from downtown skyscrapers to decaying ethnic neighborhoods.

He has had mixed results in tackling such problems as Boston's severe housing shortage. While the city financed construction or renovation of more than 1,000 moderate-priced apartments last year, developers moved to convert another 4,000 units to condominiums. Flynn's plans to extend rent controls also fell short.

But he has put in place a "linkage" program that requires downtown developers to put money into a fund to be used for neighborhood housing. After much litigation and delay, the $37 million fund has earmarked $7 million for seven neighborhood projects that are finally getting under way.

Imperfect record or not, Flynn "has convinced the voters that he has done a better job as mayor than anyone could possibly have expected," Goldman said.

"I have a gut feeling for this office," Flynn said. "The issues that are important to me are right here in the office of mayor -- public housing, jobs, fixing hoops on basketball courts for kids. Nothing fancy, just those basic issues."