The imperiled La Ronda mansion in Bryn Mawr could be rescued from demolition, but its would-be preservationists face a daunting economic challenge: raising an average of $3,000 an hour from now to September.

That's through donations, during a recession.

A Lower Merion decision Wednesday night reduced the drive to save the historic castle-like villa to a fund-raising race against the looming Sept. 1 issuance of a demolition permit.

The owner, who has declined to come forward, said through his attorney that he would entertain offers. The asking price is thought to be around the $6 million paid for La Ronda in March, and preservationists are optimistic that their efforts could echo the high-pressure saves of the Glenmede mansion and Thomas Eakins' painting The Gross Clinic.

With 88 days to go, though, experts are less sunny.

"My initial reaction is there's just no way that an organization in this economy is going to raise $6 million to preserve a historic house," said Laura Otten, executive director of the Nonprofit Center at La Salle University. "One of the messages we're hearing very clearly is that most individuals and corporations that give charitably are focusing on more basic needs: food, clothing, and shelter, if you will."

The immense mansion, designed by famed south Florida architect Addison Mizner, was built by leather-goods magnate Percival Foerderer in 1929 and is revered among architectural enthusiasts for its Spanish design.

Jean H. Cutler, director of the state Bureau for Historic Preservation, called it irreplaceable and "the region's finest example of Mediterranean Revival architecture" in a letter to Lower Merion officials.

La Ronda's owner plans to raze the estate to build a 10,000-square-foot house for his family.

According to the owner's attorney, Joseph Kuhls, he has not indicated to township commissioners a willingness to be talked out of the plan to save the estate, so preservationists have pinned their hopes on getting the house bought ahead of the demolition permit's issuance.

On Wednesday night, township commissioners said there was no legal reason to deny the permit, but several of them are working to establish a foundation to collect pledges to buy La Ronda.

Similar efforts have succeeded as the sprawling Main Line estates of the Gilded Age face modernization. Two years ago, and less than two miles from La Ronda, a buyer turned up to rescue the imperiled 16-acre Glenmede estate for $9.5 million.

"If the owners are honestly willing to entertain an offer from a conservation buyer, the odds are very high," said Mike Weilbacher, executive director of the Lower Merion Conservancy. "We think a buyer can be found."

The mansion's new owner, though, has denied a request to bring in high-end real estate brokers or other outsiders to help shop the place around. So Weilbacher and other preservationists are sharpening their own sales pitches, couched in sentiment and history rather than personal inspection.

For example:

"If you are looking for a large home, here's a large home that's a work of art at the same time," Weilbacher said. "I think this building is ready to be lived in. Does it need work? I don't know. But it has been lived in for 80 years."

Barring the sudden appearance of a benevolent plutocrat, the preservationists are casting a wide net for small donations. There is recent precedent for success there, too: Arts patrons raised $37 million in 45 days in 2006 to keep The Gross Clinic in Philadelphia.

"Is there the wealth on the Main Line to raise this kind of money if they feel so compelled for this cause? I don't doubt it," Otten said. "In this economy, the question is, 'What is the cause?' "

No clear goal has emerged for La Ronda, despite lots of talking.

"It could be a nice little hotel, a bed-and-breakfast," said Jerry Francis, president of the Lower Merion Historical Society. "It's laid out beautifully for that."

The historical society is collecting pledges to buy La Ronda while the foundation that township commissioners envision clears legal hurdles.

The preservationists have not begun cold-calling potential donors, so the pledge count stands at one: an unsolicited call from a woman who offered a six-figure contribution.

"We're pleased about that because it does suggest that our supposition that people really care about this situation is accurate," said Bruce D. Reed, president of the Lower Merion Township Board of Commissioners and a chief backer of the fund-raising effort.

The effort, Reed said, relies on drawing national support for La Ronda, and there are some indications it is working.

Stephen Sondheim, whose musical Road Show, about the adventures of Mizner and his brother Wilson, won awards during an Off-Broadway run last year, is aware of La Ronda's endangered state, said his music administrator, Sean Patrick Flahaven. And Foerderer's grandson, Percival Foerderer Ames, personally made the case on Wednesday.

Ames, an architect, stood beside an oil portrait of his grandfather and waxed poetic about the mansion's value.

"Call me naive," he said, "but I guess I'm sort of appealing to you from the artistic side of things."

Contact staff writer Derrick Nunnally at 610-313-8212 or dnunnally@phillynews.com.