Prince William's new county executive, James H. Mullen, announced yesterday a massive reorganization of the county's 2,000 staff members, which will begin with cuts in the number of top managers.

Mullen, who has been in office two months, said he will restructure all public safety, development and budget-related departments by the end of November, and reorganize the rest of the staff next spring.

Some county officials said the reorganization all but forces the departure of Deputy County Executive Connie Bawcum, who had served as acting county executive for eight months until Mullen's arrival in August, is well-regarded among staff members and citizens, and was herself a top contender for the job Mullen got. Bawcum could not be reached for comment.

The cuts are more to increase efficiency than to save money, Mullen said.

Although Prince William is facing budget shortfalls like other Northern Virginia jurisdictions, Mullen has said he hopes to avoid major layoffs.

Many in the county administrative offices attributed the restructuring to Mullen's efforts to impose his own stamp on the government. The announcement comes only three weeks after two top finance officers were allowed to resign.

Many county employees said they have felt under siege for nearly a month. All asked not to be quoted by name, for fear of angering their new boss.

"I can't say enough good things about" Bawcum, said one county employee. "But a manager has his or her prerogative to put his or her team in place."

Mullen said yesterday at a hastily organized news conference that he hoped "to reduce the layers of government and the perception of bureaucracy . . . {and} give more decision-making authority to the departments."

Yesterday's announcement reshuffled the jobs of about 10 people, and replaced both deputy county executives with one assistant county executive position, which will not be filled for several weeks, Mullen said. County officials close to Bawcum said they doubt she would apply for the job. The other deputy, Lawrence D. Hughes, may be a candidate, sources said.

Mullen said the new plan gives greater priority to economic development and transportation, key issues in this bedroom community of 230,000 where 55 percent of workers face long commutes on crowded roads.

Mullen said he inherited a top-heavy administration from his predecessor, Robert S. Noe Jr. In addition to two deputies and six assistant county executives, six other administrators now report to Mullen.

The first stage of Mullen's reorganization eliminates one position and reshuffles others. The November phase will probably include grouping other departments into teams, each headed by a department chief on a rotating basis, Mullen said. For example, all the public safety-related departments would be headed by the police chief for one year, then head of fire and rescue the next. Now, public safety department heads report directly to the county executive.

The final stage will involve boards and authorities not set up by the county executive, Mullen said. Changes may require new laws.

The supervisors were told of the changes behind closed doors on Tuesday, and most said they felt Mullen should have a free hand.

"The supervisors should not be involved with this. Whatever Mr. Mullen's decisions are, I support them," said Supervisor Hilda M. Barg (D-Woodbridge).

"We employed Mr. Mullen to run the county, and we will back his moves," said Supervisor William J. Becker (R-Brentsville).