In reorganizing the federal bureaucracy, President Carter is preparing to make the world's largest omelet without breaking any of the nearly 3 million eggs involved. Some government insiders say he cannot succeed.

In the last two weeks, Mr. Carter has been visiting the headquarters offices of major federal agencies and talking to large group of employees. He wants their support for his reorganization and wants to reassure employees that individuals will not be hurt as agencies are combined, restructured, abolished and/or streamlined.

The President has assured Commerce workers that nobody will lose a job, pay or grade standing. He told Housing and Urban Development aides nobody will be hurt or demoted because of changes. He said persons with job-related problems because of his reorganization should contact him personally. That should prove interesting.

Some key personnel officials, administrators and budget officers are shaking their heads. They think the President means well and means what he says - But they wonder if he knows what he is saying.

As an example, last Thursday Carter told cheering HUD workers:

" . . . No federal employee will be discharged because of reorganization. None will be demoted because of reorganization. There might be some need to transfer people from one job to another without any loss in your pay or seniority status. If you have to be transferred to another different job, you'll given training to meet the needs to that new job commensurate with your abilities, at government expense . . ."

Earlier, at the Commerce Department, Carter told employees:

" . . . Changes in the structure of government will not adversely affect your own careers under any circumstances. If it ever does, you contact me directly . . ."

Those promises are welcome to government workers, but many old-timers wonder if business can, or will, be conducted that way. Many are worried that employees will take the promise to mean that job classification studies, under way for months, will not result in downgradings because studies find that the jobs were overgraded years ago.

Hundreds of federal employees in the Washington area have been downgraded in recent months as agencies found alleged errors made years ago in setting the pay and responsibilities for positions.

The personnel director of an agency with more than 90,000 civilian workers said Carter cannot deliver on his promise of making a major reorganization without significant downgradings and job disruptions.

"When you reorganize, you have to look at your grade structure. We did it in my place and found 50 to 60 per cent of the upper level jobs in one area were overgraded," the director said.

"The only way it could be done is if Carter follows the pattern of his Georgia reorganization and layers over a new level of command. But that and mergers can create two heads in one job. Unless you look the other way and shelve people until somebody retires, dies or quits, you are going to have two people, in some cases, in one job, or somebody stuck off in a corner doing nothing," the director said.

Another personnel official said a painless reorganization is possible only if Carter directs agencies to ignore temporarily civil service rules that require proper job classification for a period of time until incumbents, who would have been demoted, leave or find other jobs in the agency at their same grade.

Another personnel expert disagreed. He said much would depend on the extent of the reorganizations but that a reorganization may be made without demoting people "because of the reorganization" if the agency sets out to do it that way. He said he recently eliminated five Grade-15 and one Grade-16 jobs in his section of about 100 people and "nobody got hurt." Such shuffling would be tougher in an agency of 100,000 he said, but it can be done.

If Congress agrees to all or some of the President's reorganization proposals, much shaking up and shaking down will ensure this year. It might be interesting to keep copies of Carter's job-protecting statements, plaster them on the walls of the personnel offices and, one year from now, compare promises with delivery.