Philadelphia may not have had its last Mayor Street, nor perhaps its last Mayor Green.

In the last few months, their sons - Sharif Street and Bill Green - have built impressive fledgling political bases as they run for at-large seats on City Council.

They are arguably the two Council challengers with the best shot to win on May 15, thanks in no small part to fathers who have given them instant name recognition, enviable connections, and lifelong schooling in the art of Philadelphia politics.

It's a potent combination, as mayoral sons Wilson Goode Jr. and Frank Rizzo can attest. They already serve on Council, creating the distinct possibility that four of the chamber's 17 seats could be held by sons of the city's mayors.

Street and Green aren't openly trying to follow their fathers into the mayor's office, at least not yet. But their names, the support they have gathered, and their own statements suggest they are open to the idea.

"I certainly wouldn't rule that out," Street said. "But that's a long way off."

Green was more circumspect.

"I don't intend to try to stay on City Council my entire life, but whether or not I try to get involved in another political act, I can't say," Green said.

Green and Street may both well lose on May 15. There are 19 Democrats competing for five at-large seats, including the five incumbents and a handful of other well-financed and -organized challengers.

But there is the sense that, win or lose, Green and Street won't be leaving Philadelphia's political stage anytime soon.

"Why do doctors' children decide to become doctors? Or why do lawyers' children decide to become lawyers? They've seen it in their house, they understand it, they know what's involved," Green said.

Yet Green has not always been about politics first.

His first job - which began abruptly when he dropped out of St. Joseph's University at 19 - was trading options at the London Stock Exchange, a career he continued in Amsterdam and New York.

Later, Green completed his undergraduate education at Auburn University before enrolling in the University of Pennsylvania School of Law.

"The advice my father gave me was, don't ever be dependent upon an election for your livelihood; you need to be an independent person," Green said.

Green and his family moved to Atlanta, and returned to Philadelphia in 2005. Some analysts have wondered whether his recent return is a political liability. Not so, Green said.

"I think it's one of my greatest assets. I've seen how other cities are handling similar problems far more successfully then we are in Philadelphia," said Green, who works at the law firm Pepper, Hamilton L.L.P.

As a candidate, Green is most comfortable talking about the city's big-picture problems: the economy, job creation, taxes and so on. He is impatient when discussing polls, ballot position, and other electoral minutiae that so obsess the city's political class.

But he always chooses his words carefully, couching his criticism and making a clear effort to be diplomatic.

His father? Not so much.

"Legislation is serious and sophisticated business, and I could show you again and again how Council messes it up," William J. Green III said in an interview at his son's campaign headquarters last week.

"Frankly, they haven't been bright enough, and they need somebody in there that's a crackerjack lawyer, has a good brain, is politically sophisticated, and has seen it since he's a child."

As he said this, the elder Green, 68, beamed at his 43-year-old son as though he had just won a Little League championship.

"I am proud, and I think, if he's elected, everybody's going to be proud, because he's going to make a mark so fast and so strong that they'll be stunned," said Green, who served as mayor from 1980 to 1984.

The younger Green blushed a bit. A little later, as his father fired off another shot at City Council, the candidate sighed, shook his head, and planted it in his hands.

"Does that mean I should stop talking?" the elder Green asked, chuckling. "Sorry, son," he said in a stage whisper.

The former mayor answered one last question. Would he like to see his son become mayor?

"I will pray every day that doesn't happen," he said before erupting in laughter again.

Many of Sharif Street's earliest memories are political ones, and not all of them are pleasant.

The clearest is an episode from South Philadelphia, circa 1979. Sharif and his father were in the back of a truck, campaigning against the charter change that would have let Mayor Frank Rizzo run for a third term.

Sharif Street was five years old. "People were throwing stones at us," he said.

Even that early, Street said he knew he would follow his father into politics. It's a path the 33-year-old hasn't veered from since: president of the student body at Central High School, leader of the student senate at Morehouse College, president of the Penn Law Democrats, legislative aide to State Sen. Shirley Kitchen, Democratic committeeman, founder of a political action committee, and so on.

"I've never found politics intimidating. I understood it, I knew it naturally," said Street, who now works at the law firm Wolf, Block, Schorr & Solis-Cohen L.L.P.

His first foray into electoral politics was a losing campaign for the state House in 2002. After that defeat, Street was coy about his plans, but many considered it inevitable that he would seek a seat on City Council, the chamber his father worked so masterfully for 17 years.

As the mayor's son, he has undeniable advantages heading into May 15. But being a Street has its liabilities as well. Sharif Street has had to deal with the sideshow Council candidacy of his uncle, T. Milton Street, as well as frequent attacks on his father's performance by the mayoral candidates. "I've tried to make the best of that reality without spending a whole lot of time thinking, 'What if I were born the son of somebody else,' " Street said.

When he speaks, Street sounds a lot like his father: Their cadence is similar, even their word choice. But Sharif Street comes across as much less guarded than his father, a trait that has helped him maintain cordial and even friendly relationships with many of his father's opponents.

Through a spokesman, Mayor Street "respectfully declined" to be interviewed for this article, which is consistent with his approach to this Council race. The mayor has made few high-profile campaign stops with his son.

But that does not mean he is not involved, Sharif Street said. The mayor has given him advice on "how to be a good father and husband" while campaigning, as well as political tips. Mayor Street's infamous attention to detail rears its head as well, the younger Street said.

"He spends a whole heck of a lot of time talking about how to arrange an office, how many paper clips you need, what color ink you should have, should you italicize," Street said.

"Sometimes, he's a great help. And, you know, other times, he's a dad."

Contact staff writer Patrick Kerkstra at 215-854-2827 or pkerkstra@phillynews.com.