Contract talks between the United Federation of Teachers and a nonprofit agency that serves patients with cerebral palsy have reached an impasse. Union officials said their members might walk off the job if the two sides cannot arrive at an agreement by the end of this month.

“We’re not looking to strike, period. But we haven’t ruled anything out,” a union special representative, Ilene Weinerman, said.

The agency, United Cerebral Palsy of New York, serves about 10,000 city residents who suffer from chronic conditions that affect muscle coordination. The agency receives more than 90% of its budget from the federal, state, and city governments, according to its Web site. United Cerebral Palsy reported a budget of more than $76 million in fiscal year 2003, the last year for which figures were available.

Ms. Weinerman said some agency employees earn less than $9 an hour and work more than 30 hours a week without health benefits.

The current contract, which expires August 28, covers workers at the agency’s schools and adult day treatment programs in the Parkville neighborhood of Brooklyn, as well as employees at more than 30 residential care facilities across the city.

Another union special representative, Howard Schoor, said a new contract must include workers at two additional adult day treatment centers, in Chelsea and in Bensonhurst, who recently voted to join the union. “It’s going to be all or nothing,” he said.

Today the National Labor Relations Board is scheduled to hear a complaint filed by the union members about a 46-page booklet distributed by the agency earlier this year. Ms. Weinerman, a former psychologist at the agency, said some members received the booklet during their shifts and were instructed to sign a receipt form immediately. The form stipulated, “policies may be revised from time to time, with or without prior notice.”

The agency previously sought to convince the labor board that teachers at its Brooklyn facilities are “statutory supervisors” and therefore ineligible for union membership. The board rejected that argument in a ruling last September.

Mr. Schoor accused the agency of diverting funds from care for patients with cerebral palsy in a challenge to the board’s 2004 ruling, in a motion scheduled to be heard by a federal appellate court next month. He said the union has estimated that the appeal will cost the agency $250,000 in legal fees.

The agency’s chairman, Jerome Belson, who is head of a Manhattan based real estate firm, is currently on an Alaskan cruise and is unavailable for comment, his secretary said.

The president of the agency’s board of directors, Martin Hausman, who is head of a Bronx-based industrial machinery firm, Hedco Equipment, said he is “not informed” on contract negotiations and referred questions to the agency’s executive director, Edward Matthews.

Mr. Matthews did not return several messages left at his Manhattan office last week, although a secretary acknowledged that he worked out of the office on Tuesday and Thursday.