They were developers, Realtors and retailers and nearly all of them had one thing in common:

But for nine or 10, almost none were registered to vote in Philadelphia.

They weren't necessarily campaign contributors, either, and the event was not a fund-raiser.

But that doesn't mean that either candidate for mayor could afford to be absent.

Nope. If you're going to be mayor in Philadelphia, you need these guys on your team.

"They represent important development interests in the city of Philadelphia," said Republican mayoral candidate Sam Katz yesterday after addressing several hundred members of the International Council of Shopping Centers, who were holding their annual regional meeting at the Convention Center. "If we want to interest them in Philadelphia, we have to promote Philadelphia to them . . .That's what the mayor is supposed to do."

ICSC is the largest retail organization in the country. Its conferences attract developers and retailers who come to make deals, lease retail space and show off their projects to partners and competitors. Ultimately, it's these people who will either bring real estate investment to the city - or decide to take it elsewhere.

And while business decisions are complex, based on market constraints, location and consumer demand, who's in charge at city hall is crucial.

If the mayor is unacceptable to business interests, "the spigot will cut off" for private investment in the city, said Joseph Coradino, the executive vice president and chief operating officer of Pennsylvania Real Estate Investment Trust. "At the end of the day, who becomes mayor is very important to these people. . .Whether a mayor is pro-development or not impacts the ease of doing business."

In their speeches yesterday, neither candidate departed much from their usual campaign schtick. Both Katz and Democratic candidate John Street promised business-friendly laws and an open-door government that would welcome investment.

They touched on schools, crime, guns and taxes and the other major campaign issues. And Street used the platform to advertise his endorsement from District Attorney Lynne Abraham, which was announced earlier in the day.

But ultimately, it wasn't endorsements or political platforms that many of the attendants said they wanted most from yesterday's speeches.

What they wanted was reassurance.

"There's a lot of concern," among real estate types about what will happen when Mayor Rendell leaves office, said Greg Whedbee, a broker and developer with Century 21 Advance Realty in Berks County. "Will [the next mayor] continue what Ed Rendell has done? Will he be out there being a deal maker?"

The answer has many on edge, he said. "There's a lot of projects on the drawing board that could either fly or die based on how the next administration looks at them."

Katz and Street appeared together again last night at a candidates forum sponsored by the Center City Residents Association, held at Graduate Hospital.

Sitting side by side, Street and Katz spent most of their time on how to fix the troubled schools: Katz said he wants the right to appoint school board members which would make him more accountable for the system. Street said that would make the district a bastion for patronage.