In 1958, Lester L. Mitchell -- just 18 years old -- joined the General Services Administration as a "clerk-typist" in the agency's federal supply division. For most of the time since then, Mitchell moved on a fast track as one of the rising stars in the federal bureaucracy.

Mitchell pulled off a coup in 1981 by getting then-GSA administrator Gerald P. Carmen to name him assistant GSA administrator for the office of federal supply and services, a post traditionally reserved for political appointees and not career civil servants.

Inside GSA, Mitchell developed a reputation as a doer; a consummate executive who mastered the art of delegating responsibility and one who could squeeze the most from his hand-picked program managers.

Mitchell made it the hard way, earning a degree in finance and accounting from the Benjamin Franklin University at night. Eventually, he would receive an award from President Reagan for outstanding achievement for his work with the federal supply service.

But earlier this month, at 44, Mitchell resigned abruptly from his last job at GSA -- commissioner of the Public Buildings Service. He said he plans to work in the private sector. There are options, he said, but nothing firm, nothing he can discuss openly.

Effective Feb. 2, Mitchell will be replaced by Robert J. DiLuchio, a 13-year veteran of GSA who is now serving as deputy associate administrator for operations.

The story of the last 13 months for Lester Mitchell is that of a man embroiled in a difficult situation largely not of his own making. He became a man in the wrong place at the wrong time, facing an uncooperative bureaucracy armed only with a background in supply -- not in real estate.

A GSA official now says that the decision to name Mitchell to the Public Buildings post "may have been the single stupidest thing that Carmen ever did at GSA."

The story began in December, 1983, when then-commissioner Richard O. Haase resigned to return to private business. Carmen decided that a good manager -- Mitchell -- should follow the creative and often free-wheeling Haase.

And initially, Mitchell was to be a temporary commissioner. Carmen had decided to leave in February, 1984 and Mitchell -- it is said -- was supposed to come in, build good management systems and then go back to federal supply. But Carmen's successor, Jack Courtemanche, wasn't nominated as soon as had been expected, and because of civil service time limits, GSA was forced to name Mitchell the permanent commissioner and to name a new permanent assistant administrator to head the office of federal supply.

In the meantime, Mitchell, in the eyes of some of Haase's appointees, began to let Haase's creative projects slide. What they saw as opportunities to buy new federal buildings were missed; leasing of unneeded government space to private tenants lost its thrust and the staffer who headed the program; and the work-space reduction program -- supposed to cut space by 10 percent -- was now supposed to save only 2 percent, GSA and outside sources said.

Mitchell sparred with the unit in the Office of Management and Budget that oversees the Public Buildings Service, and he had a run-in with the private real estate community.

People in the agency began to choose sides: for Mitchell or against.

James Stewart, executive director of PBS for operations, said Mitchell's successes included "reforming the workspace policies guiding the amount of office space people can use; providing major leadership on programs that deal with the delegation of authority from GSA to federal agencies that want to run their own buildings and in making the fire-safety program more accountable."

In a December interview, Mitchell said that when he started, "the fire-safety program was a low priority, perhaps nonexistent. No workable program addressing the important area of fire safety in federal buildings was in place. In fact, it was obvious little management attention had been paid to this important area."

The comment drew immediate criticism from colleagues, including deputy associate GSA administrator Clarence A. (Pete) Lee Jr.

Lee said that an internal report showed the safety program under Mitchell is one of the worst programs tracked by the office. One document shows that of the 10 most significant issues, only the safety program was considered behind schedule and to have management problems.

And Jerald D. Fox, a senior aide to acting GSA administrator Ray A. Kline, said Mitchell's comments on fire-safety were "absurd. We had a program that started with Carmen and Haase and it's well documented. I don't know what purpose is served by trying to take the credit."

On another occasion, staff work by Mitchell's bureaucrats on the work-space reform initiative was shot down by other GSA political leaders. At the presentation meeting, Mitchell reportedly sat "sullenly," said one official who attended. "He didn't defend himself at all," said another who was there.

As questions were raised about the increasing perception of disorder, Mitchell was accused of withdrawing behind an inner circle of advisers while shipping others out.

Ira Jekowsky, a Carmen favorite who handled PBS's budget, was moved to an office far from Mitchell's and stripped of some of his responsibilities.

William A. Clinkscales Jr., GSA's associate administrator for policy and management systems, said: "Unfortunately, he Mitchell never harnessed the PBS organization -- neither its people nor its programs."

Davis, a Mitchell supporter, said that on "several occasions, Mitchell would be 'done in' in effect, by his bureaucrats. He wouldn't understand the nuances of what they were giving him, and others in the agency would. Then they'd rip into his program. That's why he had to set up a circle of advisers." In the end Mitchell had 35 aides on the commissioner's payroll, according to a reliable source. Haase had six.

Haase, who is now with the Holladay Corp., said: "If I were to comment or criticize it from afar, my point would be that he didn't recognize the priorities of the job. The job of the commissioner is to stimulate new ideas into the form of policy. His job is to lobby Congress and the OMB on the new programs that come out of PBS."

"Les brought a good level head and a measure of dynamics to the Public Buildings Service," said Davis. "He tried to make the programs more timely and productive. To some extent he did that. That is not a job you can do in one short year."

In an interview this week, Mitchell said GSA was now providing better services to the federal agencies and that it was doing so in a more understandable and cost-efficient manner.

"I have no regrets," he said.

In a statement, Mitchell added: "I accepted the position as PBS commissioner to chart a new direction for the organization. That goal is accomplished, and I am ready for new challenges outside government."

Kline praised Mitchell, stating that he "has had a long and illustrious career with GSA and will be missed.