Congress and the White House are about to take delivery of a potential political bombshell. It is a still-secret, detailed, lengthy study on how best to bring federal, state and local government workers, who now enjoy their independently financed and more generous retirement systems, under Social Security.

One option coming from the Universal Social Security Coverage Study will jolt the bureaucracy. It would shift nine of every 10 federal workers to Social Secaurity immediately. Provious recommendations on the subject have proposed grandfathering-in people already working for the government, and mandating Social Security only for new employes.

Under that option, the only government workers who would be allowed to remain completely under the existing CS system would be those eligible to retire -- mostly people 55 and older.

In addition to drawing benefits that are two to three times higher than Social Security, federal retirees now get regular COL (cost of living) adjustments every six months. Social Security benefits are adjusted once a year. On the other hand, federal workers contribute much more to their retirement fund, and their annuities -- unlike Social Security -- are taxable.

Another option in the pending report follows the more traditional route, one aimed at pacifying the 2.7 million federal workers. It would allow anybody now in government to remain under the CS system. Persons hired after the new law went into effect would have to go under Social Security, with reduced CS benefits upon retirement to supplement their Social Security payments.

Most federal, postal and retiree groups are opposed to any form of mandatory Social Security coverage. A coalition of unions, professional associations and other organizations already has raised more than 3 million in contributions from workers and retirees to fight any "merger" with Social Security when and if Congress takes it up.

The concept of "universal coverage" (as backers prefer to call it) was once considered an untouchable item in an election year. That is because it would frighten most of the 6 million to 7 million federal, state and local government workers who are now outside the Social Security system that covers most American workers.

Aides to the president say he has not seen the study, nor has his administration decided whether to back or reject mandatory Social Security coverage for government workers. But if Congress renews its interest in mandatory coverage (members of Congress are now under the federal retirement system and exempt from Social Security), it could be seriously pushed this year.

Officials who worked on the study declined to comment on its contents, other than to stress that it is "a study, a series of options but not recommendations" for Congress and the president. Under the chain-of-command, the report, which has been in the works for 17 months, first will go to HEW Secretary Patricia Harris. She will transmit it to Congress and the president by March 31.

The concept of putting millions of public employes under Social Security is a complex, mind-blowing proposal that would require restructuring of both systems.

Federal workers, for example, can retire as early as age 55. Benefits under Social Security do not normally begin until age 62. Federal workers pay much more for their benefits (7 percent of total salary) than do persons under Social Security.

Finally, federal and postal workers argue that it is unfair to compare their CS system with Social Security. Their system is a staff retirement program, they say, and a condition of employment. Social Security never was intended to be a complete retirement income.

The fact that people under Social Security generally have a harder time making ends meet is the fault of employers -- and unions -- who failed to provide better retirement systems for them, these people argue.

The outcome of mandatory Social Security coverages will depend on how badly Congress and the Carter administration want it -- if they do -- and how hard they are prepared to fight for it.

If they do decide to push for mandatory coverage this year, federal, postal and retiree groups will have their hands full, and their coffers emptied, fighting it.