One of Washington's most successful lobbying firms disclosed yesterday that it is breaking up effective next Thursday.

Downey Chandler Inc., formed five years ago by former representatives Thomas J. Downey (D-N.Y.) and Rod Chandler (R-Wash.), had been among the city's fastest-growing firms, offering access to Democrats and Republicans in Congress.

But yesterday Chandler confirmed that he will become president of R. Duffy Wall, an 18-year-old lobbying shop acquired last year by Fleishman-Hillard Inc., the St. Louis-based public relations firm. Chandler said he will take some clients with him and that the firm will be renamed.

"It was one of those offers you can't refuse," said Chandler, who became friends with Downey playing basketball in the House gymnasium. Since he joined Downey as a lobbying partner in 1994, Chandler had been the firm's vital link to the House GOP majority. The firm's clients include Boeing Co., DuPont Co., Fuji Photo Film USA Inc., Metropolitan Life Insurance Co. and Time Warner Inc.

Chandler's GOP credentials and service on the Ways and Means Committee were assets that the firm wanted, said Duffy Wall's president, former representative Bill Brewster (D-Okla.), who also served on the tax-writing committee. The two men closed the deal this week.

"It was very difficult," Chandler said. "I told Tom, 'I know I'm going to cry when I tell you this.' And I did."

Chandler's departure "leaves a void," Downey said, adding that he will seek another high-profile Republican to replace him. "I've spoken to the clients and they seem to be happy," he said, conceding that a few would follow Chandler.

Duffy Wall suffered a dip in billings last year after the firm's namesake stepped down because of lung cancer and the firm lost three principals. Brewster said the firm had recovered from that slump and that Chandler and his clients would boost its recovery.