The top Energy Department official in charge of the nation's nuclear weapons complex, Victor H. Reis, may quit or be fired in a dispute with Energy Secretary Bill Richardson, sources said yesterday.

Contacted last night, Reis said, "As of tonight, I'm gainfully employed, and I'm going to work tomorrow. . . . I don't know for how long."

One congressional source close to Reis said the dispute with Richardson revolves around Republican proposals to reorganize the Energy Department in the wake of allegations of Chinese nuclear espionage.

The source said Reis supported a bill drafted by Sen. Pete V. Domenici (R-N.M.) to create a semiautonomous agency responsible for the nationwide complex of laboratories and plants that research, assemble and maintain nuclear weapons. Richardson is fighting for his own plan to reorganize the department by creating a new undersecretary for nuclear stewardship with responsibility for the weapons complex.

An Energy Department source, while denying that Reis had been fired, indicated that he "was on the hot seat" and may be among the employees held responsible for security failures at the labs.

Reis has run the nuclear weapons complex as assistant secretary for defense programs since 1993, when he was hired by then-Energy Secretary Hazel O'Leary.

An electrical engineer by training, he joined the Pentagon in 1989 during the Bush administration, first as deputy director and then director of the Defense Advanced Research Projects Agency. In 1991, he became head of Defense Research and Engineering, before joining Energy.

"It is no secret that Secretary Richardson has not been satisfied with the emphasis given counterintelligence and security at the labs, and Vic Reis has been the person in charge for the last six years," a department official said. "He clearly has had responsibility for what went on."

According to one White House official, however, Reis is "in hot water" because of his open support for creating a semiautonomous nuclear agency. A presidential adviser said it was "well known that Reis had told people he supports the congressional plan."

Richardson could not be reached for comment last night. He was meeting employees at the labs to assure Asian American workers that they will not be unfairly targeted as security risks. Richardson also met with the heads of Los Alamos, Sandia and Lawrence Livermore labs to discuss the reorganization plans.

At Los Alamos, employees questioned polygraph tests that Richardson has said as many as 5,000 scientists and workers with top-secret clearances must take. One worker suggested that Richardson take a polygraph himself to "lead by example," the Associated Press reported.

"I might," Richardson said, adding, "I am prepared to take it."

Richardson, who has already established a "security czar" and a director of counterintelligence to bolster security, has said he abhors the idea of a semiautonomous agency because it would be "a new fiefdom" within his department.

An Energy Department spokesman said that as of yesterday, Reis "has not been fired." But, the spokesman added, "I don't know about tomorrow."