IN THE STORY line of this year's campaign for district attorney, Dan McCaffery has been tagged more than once as the heavy.

Early on he had the backing of Local 98 of the electricians union, a powerful force in local politics known for heavy contributions and in-your-face tactics - most recently the anonymous distribution of racially and religiously tinged leaflets in the 2007 mayor's race.

After five Democratic candidates filed to run, McCaffery tried to get front-runner Seth Williams removed from the ballot, on grounds that Williams failed to disclose campaign expense reimbursements as income. It turned out, McCaffery himself had dealt similarly with expense reimbursements.

Last month, the Daily News raised ethical questions about a real-estate deal in which McCaffery had purchased a house from an estate handled by his own law firm, flipping the property for an $89,000 profit in a matter of months.

McCaffery has just one major plea for reporters and voters: Pay attention to his record and his reputation in the D.A.'s office, where he spent more than five years in the 1990s, doing a solid job prosecuting dangerous juvenile offenders and major felony cases, for just about everything short of murder.

Former colleagues in the D.A.'s office confirm what McCaffery says about himself.

"Dan was a very good trial lawyer, hardworking, nose to the grindstone," said a prosecutor who asked not to be identified, not wanting to be drawn into the public debate over who should succeed Lynne Abraham as the next D.A.

"He didn't take anything for granted," the prosecutor continued. "He had sort of a blue-collar Philadelphia attitude about his work. He was easy to get along with, trustworthy, and there was a sense of loss, a gap, when he was gone. . . . We were better off when he was on the staff."

Like many young prosecutors, McCaffery left the office after gaining trial experience, to enter private practice. In 1996 he joined an Elkins Park law firm where he still practices, mostly in commercial litigation. The firm is now known as Friedman Schuman Applebaum Nemeroff & McCaffery.

At age 44, it is McCaffery's first run for public office. But his name recognition and political relationships are strengthened by the fact that his older brother, Seamus, is a well-known judge, first elected to Philadelphia's Municipal Court, then to Superior Court and finally to the state Supreme Court two years ago.

The largest donor to Seamus McCaffery's 2007 campaign was the political-action committee run by Local 98 of the International Brotherhood of Electrical Workers, which donated $240,000. It is among the unions and law firms that have contributed heavily to Dan McCaffery's campaign, although PAC donations are limited to $10,600 annually under the city's contribution limits.

Last year, Dan McCaffery raised almost as much as his four opponents combined - an edge that could prove valuable if he is able to afford television advertising while his opponents cannot.

Dan McCaffery credits his union support less to his brother's connections than to his 81-year-old father, also named Seamus, a professional boxer and printer who emigrated from Belfast, Northern Ireland, in the 1960s, after he was severely beaten in an anti-Catholic incident.

"The name Seamus would have been too recognizable as an Irish Catholic, so he fought under the name 'Joe Boy Driscoll,' " McCaffery told the Daily News. "He fought all the way through the amateurs and became a pro."

After a layover in Montreal, the family settled in Germantown, where Dan McCaffery was born. He grew up in Rhawnhurst, his father working as a printer and a union organizer while his mother worked as a janitor in the public schools.

His father was one of the founders of Irish Northern Aid, a group that raised money among Americans to help Catholics in Northern Ireland, McCaffery said. Many of the other activists were part of the Philadelphia labor movement, particularly the building trades, which have lined up, 40 years later, behind McCaffery's candidacy, he said.

"The building-trade guys are great for me because I come from a union family," he said. But he vowed that their support wouldn't influence any decisions he makes as D.A.

"If any of those guys step out of line, believe me, out of the five candidates, I'm the last guy they want in that office," McCaffery said.

McCaffery has been less specific than most of his opponents in describing how he would change the D.A.'s office, and he's missed a number of the joint appearances at which the candidates have put themselves on display for community and civic groups.

One factor is his father's medical condition: He had heart surgery in March and an apparent stroke last month.

When he formally announced his candidacy in January, McCaffery scheduled the event in front of the Family Court building on Vine Street, calling for "an overhaul of the juvenile-justice system," in which he had spent nearly half his time as a prosecutor.

Instead of cycling prosecutors through juvenile-justice assignments on their way to other jobs in the D.A.'s office, McCaffery said, he wants to staff the juvenile unit with veteran prosecutors who want to stay there.

"These guys are rotating out as soon as they begin to learn it," McCaffery said. "If you can create a unit of dedicated prosecutors who can work with DHS [the city's Department of Human Services], work with the school truancy police, and work with all the [nonprofit] agencies over there, you'll be a lot more effective."

Another opening salvo of McCaffery's campaign was a broadside against "lazy, incompetent and uncaring judges." If elected, he said, he would create a Web site to publicize the working hours of individual judges and the sentences they dispense to convicted criminals.

In an interview the other day, McCaffery said that the volume of criminal cases and the declining work ethic of many judges had combined to undermine the justice system in Philadelphia.

"It's not about what's right and what's wrong anymore," he said. "It's about dispositions. Judges have become accountants. . . . If there are 20 cases on their list, they want to dispose of half of them, regardless of the consequences to the commonwealth or the citizens of Philadelphia. . . . Nine times out of 10, the only time it benefits anyone is the defendants."

Like the other candidates for district attorney, he says that the D.A.'s office is deciding to bring criminal charges in too many cases where it should be directing individuals to drug- and alcohol-treatment programs, or mental-health services.

McCaffery attended Catholic schools, graduating from Father Judge High School, then Temple University and its law school. He lives in East Torresdale.

Asked to identify his major accomplishments outside of work, he referred to raising his two daughters, now 11 and 18, and starting a rugby team at Father Judge, where he serves on the Board of Advisers.