Dominic F. Antonelli Jr., who started his career as a parking attendant and built one of Washington's largest real estate fortunes, is asking about 50 lenders to relax repayment terms on hundreds of millions of dollars in real estate loans that are in default or appear headed for default, his attorney, Roger Frankel, said yesterday.

One of those lenders, National Bank of Washington (NBW), has sued Antonelli because of his failure to repay $4 million it lent to him earlier this year.

Frankel said that unless the lenders give Antonelli time to work out his financial problems, he could be forced into bankruptcy.

"If all of the lenders say, 'We want our money today,' then obviously we could not respond to that and we would have no alternative to putting projects in bankruptcy and ultimately Mr. Antonelli in bankruptcy," Frankel said.

Frankel said Antonelli, who is chairman of Parking Management Inc. (PMI), and his partners did not anticipate the downturn in the real estate business when they launched many projects a few years ago.

Now, they are saddled with undeveloped land that needs to be sold and office buildings and shopping centers that need tenants, "and the market is the worst that it's ever been," Frankel said.

Some of Antonelli's problems stem from investments in 15 hotels from Florida to Pennsylvania, including Days Inns.

MNC Financial Inc., parent of American Security Bank and Maryland National Bank, has been negotiating with Antonelli over approximately $100 million in loans, sources said. MNC, which is the region's largest bank holding company, reported a $75 million loss during the second quarter because of troubled commercial real estate loans.

Throughout the Washington area, an oversupply of commercial real estate developed during the boom years of the 1980s and an economic slowdown have driven many developers to default on loans, causing banks and savings and loans to report mounting losses. The developers' difficulties have been compounded by a sharp reduction in real estate lending.

Antonelli joins Conrad Cafritz and other major real estate developers who expanded rapidly and are struggling to survive amid the downturn in real estate markets nationwide. Cafritz still is negotiating with dozens of lenders over a plan that would allow him to reschedule loan repayments.

Unlike many other major developers, Antonelli -- now in his late sixties -- sought to avoid publicity as he gained control of hundreds of millions in dollars of real estate. But his PMI parking logo has become familiar in the area and banks held him in such esteem that they lent him millions on the strength of his signature.

NBW required no collateral when it lent Antonelli $10 million in February. It accepted Antonelli's promise to repay, which also was backed by his wife, Judith D. Antonelli. As its own financial condition deteriorated, NBW demanded that the Antonellis repay the money June 28. The Antonellis have not complied, according to NBW's lawsuit filed in U.S. District Court here.

Federal regulators seized control of NBW last week after the bank's parent company sought protection from creditors under bankruptcy law. NBW and Antonelli are discussing a possible settlement to the lawsuit, lawyers said.

Real estate brokers said Antonelli has been trying to sell at least two of his Washington holdings, a downtown office building and the ground beneath the massive International Square development on K Street NW.

Despite the vastness of his holdings, Antonelli never built a large development firm. Instead, he formed partnerships with other developers. By virtue of his parking garages, Antonelli was sitting on precious development sites when real estate values soared in the 1980s. He developed some of those sites and sold others.

His close associates include Huntmar Associates Ltd. and Tri-Equity Group Inc., which are based in Fairfax. Sources said Antonelli personally guaranteed loans on many of his ventures with other developers, leaving himself vulnerable when the projects ran into financial trouble.

Antonelli over the years has been among the largest financial contributors to local politicians. As recently as last year, he and associates gave thousands of dollars to Mayor Marion Barry and D.C. Council Member John A. Wilson (D-Ward 2) through various partnerships, records show. Antonelli is a director of James Madison Ltd. and its subsidiaries, Madison National Bank and James Madison Mortgage Co. He is on the board of the developer Washington Corp.