The union representing health care workers at St. Elizabeths Hospital rejected a proposed contract with the District government yesterday, saying that it failed to guarantee that workers would remain at the same rank as a result of the transfer of the hospital from federal to city control.

In January, the city reached a tentative agreement with negotiators for six unions representing 17,000 blue- and white-collar workers, including Local 2095 of the American Federation of State, County and Municipal Employees, which represents 1,500 nurse assistants, housekeepers and other St. Elizabeths workers.

The agreement called for a 9 percent pay raise over three years, but a Local 2095 official said that union members rejected the proposal out of concern that it doesn't address provisions in the transfer agreement that caused some of their workers to lose a step in rank.

However, Mark H. Levitt, a city labor negotiator, said that the local's concerns were unwarranted, because under the transfer workers were guaranteed that they would make at least as much money as they were making previously. He said workers were placed into lower steps only to match their new salaries as closely as possible to their old.