So it comes as no surprise that the former middleweight boxer says what he'll miss most when he hangs up his gloves tomorrow will be slugging it out with Philadelphia's elected monarchs.

"They're all tough people, and very smart," says Cronin, 64, president of the city's white-collar municipal union since 1980 and a social-justice activist since his early 20s.

"I like scrappers. The struggle, the jockeying back and forth, it's an adrenaline rush."

For Cronin, the rush has lasted an unprecedented nine terms, six mayors, a zillion hours of contract negotiations, and more than a few death threats.

It all comes to an end tomorrow night, when the 6,500-member District Council 47, American Federation of State, County and Municipal Employees, elects Cronin's successor.

Oh, boy, is he ready. He recently overheard a conversation between two young members in which one asked, seriously, if Cronin were president for life.

"I thought, 'Wow, it has been a long time,' " he says. "I might be getting stale. People can stay around too long - presidents of the United States, governors, and particularly, union leaders."

Dressed in a black T-shirt and black trousers, the buff union man (he bench presses 235 pounds) is sitting in his half-empty District 47 office in Center City. Moving boxes are scattered throughout.

Most of Cronin's personal papers have been given to Temple's labor archives. Old strike posters from such disparate organizations as the NFL Players Union and SEPTA are piled on a table.

"I've pissed a lot of people off," he says quietly. "I have no regrets. Working people have to struggle for any measure of justice in this society, whether it's civil rights, minimum wage, AIDS funding or labor. Nobody gives it to you."

Especially if you don't look the part.

With his trademark straw hat, Cronin bears little resemblance to "the typical union leader who likes to roll up his sleeves and go to war," says Buzz Bissinger, author of A Prayer For the City, a chronicle of Mayor Ed Rendell's 1992-96 first term.

A ruddy Irishman, Cronin says he wears the hat to look cool. The real reason, however, is to protect his punum after a bout with skin cancer five years ago.

Hat or no hat, Cronin "is a great, old-fashioned labor negotiator in the best sense of the word," says former Mayor Bill Green (1980-84). "He cares about his people and fights like crazy for them."

Crazy like a fox. Worldly and well read, Cronin "brought a level of intellect to negotiations that will be very hard to replace," says David L. Cohen, Rendell's chief of staff for 51/2 years.

Judging by his bloodlines, Cronin was genetically destined to be a revolutionary.

His father, Joseph, was a Philadelphia public defender and lifelong champion for the underdog. Among his many arrests was one with Tom at an antiapartheid demonstration in Washington in the mid-'80s.

"That's my idea of a father-son bonding experience," Cronin says.

His mother, Maryann, spent several weeks in a Nevada jail, along with Daniel Ellsberg, for trespassing on a nuclear test site - in her 70s.