As Democrats belatedly ramp up the search for a top-tier challenger to Sen. Arlen Specter (R-Pa.), party leaders have focused recruiting efforts on a group of nontraditional candidates with unique profiles and personal fortunes in hopes of toppling the longest-serving Senator in state history.

Democratic Senatorial Campaign Committee Chairman Jon Corzine (N.J.) has met separately with both Pennsylvania Gov. Ed Rendell (D) and Philadelphia Mayor John Street (D) to discuss potential candidates who might fit the bill.

Those leading the list so far include the sister-in-law of Revlon cosmetics mogul Ron Perelman, Philadelphia 76ers general manager Billy King and the head of a Pennsylvania nonprofit environmental group.

Corzine has spoken with both King and Marsha Perelman, the president and CEO of a Philadelphia energy company, among other potential candidates who have not closed the door on a Senate run, according to several Democratic sources in Washington and Pennsylvania.

“We’re in the very exploratory stage,” Corzine said last week. “I haven’t spoken to all of them, but I’ve spoken to most of them.”

Democrats are taking such an unconventional approach to the race that even Pat Croce, a colorful athletic trainer who went on to become president of the 76ers before retiring in 2001, has been mentioned as a potential candidate.

The stakes are high for Democrats, who believe they have an opportunity to unseat Specter next year because he is facing a potentially draining primary and a presidential election year. Rep. Pat Toomey (R-Pa.) is running to the ideological right of the moderate Specter in an April primary.

But with Specter showing $7 million in the bank as of March 31, Democrats’ ability to find a candidate with some personal wealth, or the ability to raise large amounts of cash, has taken on increased importance. They also realize that conventional candidates have tried and failed to beat Specter in the past.

“I think the first sense is to look beyond the traditional type of candidate, either from a money perspective or a profile perspective,” said one Democratic consultant.

Perelman is the founder and chief executive officer of Woodforde Management Inc., an energy company based in Wynnewood, Pa.

She is a former president and chief executive officer of the Philadelphia Zoo and comes from a well-known Philadelphia-area family that has been a major donor to arts projects in the City of Brotherly Love.

In 1999, she contributed to the presidential campaigns of former Sen. Bill Bradley (N.J.) and then-Vice President Al Gore, both Democrats, as well as the campaign of now-Sen. Hillary Rodham Clinton (D-N.Y.).

According to one source, Perelman is sorting out whether she wants to run and “has neither fully engaged herself in it, but has not shut the door on the possibility.”

King, the 37-year-old general manager, has expressed an interest in the Senate race and has spoken with Corzine about running. King, who has been with the 76ers since 1997, was once a standout player at Duke University, where he was a political science major.

The prospect of King taking on Specter — a huge 76ers fan — has already generated a good deal of excitement within Democratic circles.

“He brings a lot of things to the table in a race like that,” said one Democrat. “I think in general there’s been some excitement about the idea of Billy King.”

King would not be able to self-fund a race, but strategists and consultants say that his high profile and connections to wealthy athletes would provide him with a solid fundraising base.

But King remains untested politically and others wonder whether his ability to guide a winning team would translate into beating a four-term incumbent.

“Could he dribble past Arlen Specter? Yeah, on a basketball court, but could he do it in a campaign?” said Pennsylvania Democratic consultant Larry Ceisler.

Still, it is unlikely King would take a hard look at running until his team finishes post-season play. Heading into Friday night’s game, the 76ers’ playoff bid was still alive.

John Hanger, the president and CEO of PennFuture, a nonprofit grassroots environmental advocacy group, has also expressed a strong interest in the race, although he too does not appear to have the ability to self-fund.

“We’ve been through a race against Specter where we’ve had an underfinanced candidate,” said the Democratic consultant. “That model does not seem to work very well against Specter.”

Among the other potential Democratic candidates mentioned are University of Pennsylvania President Judith Rodin, state Sen. Connie Williams and state Treasurer Barbara Hafer, a Republican who endorsed Rendell’s gubernatorial bid.

Both Williams and Hafer have indicated they are not interested in running, although both are viewed as potential challengers to Sen. Rick Santorum (R-Pa.) in 2006.

Rodin, meanwhile, is described as Democrats’ “dream candidate,” although most political observers believe it is unlikely she would run.

State Auditor Bob Casey Jr. and former state Sen. Allyson Schwartz have also been mentioned as potential candidates, but both have their eyes on other statewide offices next year. Casey has indicated that he will run for state treasurer, while Schwartz is looking to succeed Casey as auditor general.

Peter Buttenweiser, a philanthropist from Philadelphia who has been a huge DSCC soft-money donor and is a close confidant of Minority Leader Tom Daschle (D-S.D.), is helping in the search for a candidate. He described this stage of the recruiting search as “slightly frantic activity” that is “an active and organized process.”

Perhaps most importantly, Corzine and state Democratic leaders feel that Rendell would not be an obstacle to any challenge to Specter, who has been a close friend of the governor for more than 30 years.

When Specter was the Democratic district attorney in Philadelphia in the late 1960s and early 1970s, he hired Rendell as an assistant DA. The two were neighbors in the city’s exclusive East Falls section until Rendell moved into the governor’s mansion in Harrisburg in January.

In Specter’s 1998 campaign, aides to his opponent, a little-known state Senator from the southwestern corner of the state, William Lloyd, complained that Rendell prevented his supporters in the Philadelphia region from working on Lloyd’s behalf. At one point Specter even used shots of Rendell in his campaign ads in the fall of 1998.

Now, after a stint as chairman of the Democratic National Committee, Rendell plays a higher-profile role in his party. Corzine said the governor’s standing as a good Democrat would be enough to push him to help recruit an opponent to Specter.

“Ed has a very significant national posture, one I think he would want to enhance,” Corzine said.

A Philadelphia-area Democratic strategist agreed that Rendell would take a much different approach to this race against Specter, noting that the political farm team of Pennsylvania Democrats is almost completely depleted from a decade of GOP dominance in statewide races prior to Rendell’s successful 2002 gubernatorial bid.

“There are certain things that are incumbent upon him to get done, like rebuilding the Democratic Party,” the strategist said.

Also, despite the close Specter-Rendell bond, Specter played the part of loyal Republican in the 2002 race and campaigned on behalf of Rendell’s opponent, Attorney General Mike Fisher (R).

That victory by Rendell has apparently altered the perception of how Pennsylvania Democrats believe they can win. In years past, many party operatives in the culturally conservative Keystone State argued that only a pro-gun, anti-abortion-rights Democrat could win statewide, a view epitomized by the late Gov. Bob Casey’s (D) victories in 1986 and 1990.

But every name floated so far for the Specter race has been a social liberal from that southeastern corner of the state around Philadelphia.

And Democrats hope that Specter’s recent defense of Santorum’s support for criminalizing homosexual acts would eat away at the former Philadelphia district attorney’s image as a social moderate.