The nation's 2.6 million federal and postal workers could change the balance of political power in many state and city races if Congress and the White House permit them to take active roles as campaign fund raisers, managers or candidates.

Federal workers now are limited to "passive" political roles by the Hatch Act. Many federal and postal unions, the AFL-CIO and key congressional Democrats are working to liberalize the law to permit civil servants to get into partisan politics, during their off hours, for the first time in 38 years.

It could have a profound impact on American political campaigns at the local, state and national level.

Many Republicans oppose Hatch Act changes because they suspect the bureaucracy is overwhelmingly Democatic in sentiment. Voting patterns around Washington (which has 347,000 civil servants) don't bear that out, although it is safe to speculate that federal and posal union members - who would probably be the most active campaign workers - are generally Democratic in sentiment.

There isn't a village or hamlet in the country that doesn't have somebody who works for the government - an Agriculture Department agent, forest ranger or a part-time postmaster or rural letter carrier. In many areas - especially the South, Midwest and far West - federal workers are among the best paid citizens, and by virtue of their training and jobs, often are among the town's most influential citizens.

Some cities, like New York (104,000 federal government workers), Philadelphia, (75,000), Los Angeles (70,000), and San Francisco (60,000) have very high federal-employee populations. But it is in the smaller towns where a de-hatched federal work force could have its greatest impact in both numbers and influence in local politics. Consider the federal-employee populations for these cities:

Albany-Troy, N.Y. 9,600; Alburquerque, 11,600; Anaheim, Calif., 8,500; Anchorage, 7,900; Anniston, Ala., 5,900; Atlanta, 30,000; Austin, Tex., 6,100; Bakersfield, Calif., 9,100; Baltimore, 56,000; Biloxi, Miss., 6,100; Boston, $35,400; Buffalo, 10,500; Charleston, S.C., 15,000; Chatanooga, 7,800; Cincinnati, 13,500; Columbia, S.C., 6,600; Dayton, Ohio, 25,000; Dallas-Fort Worth; 28,000; Denver, 30,000; Detroit, 30,000.

El Paso, 7,200; Fayetteville, N.C., 6,100; Fresno, Calif., 6,900; Harrisburg, Pa., 13,500; Honolulu, 25,000; Hunstville, Ala., 15,000; Kansas City, 24,000; Indianapolis, 17,000; Lawton, Okla., 4,000; Lexington, Ky., 7,200; Little Rock, 6,900; Long Branch N,J., 11,400; Macon Ga., 17,000; Memphis, 15,000.

Miami, 13,400; Minneapolis, 19,000; Milwaukee, 11,000; Montgomery, Ala., 5,700; Nashville, 8,000; Norfolk-Newport News, 33,000; Newark, 23,000; Oklahoma City, 30,000; Omaha, 8,000; Phoenix, 11,000; Pittsburgh, 18,000; Raleigh-Durham, 6,100; Richmond, 9,500; Roanoke 3,200; Rochester, N.Y., 5,700; Sacramento, 26,000; Monterrey, Calif., 5,500; St. Louis, 34,400; Salt Lake-Ogden, 33,000; San Antonio, 37,000; San Diego, 35,000; San Jose, Calif., 9,700.

Seattle, 17,500; Stockton, Calif., 6,000; Syracuse, N.Y., 5,000; Tacoma, Wash., 8,000; Tampa-St. Petersburg, 10,500; Tucson, Ariz., 5,800; Utica-Rome, N.Y., 5,000; Vallejo-Napa, Calif., 14,000; Wilmington, Del., 5,200, and Youngstown, Ohio, 1,000.

In the past, politicians have tended to view the federal bureaucracy as a sure-fire, vote-getting whipping boy to be pummeled and castigated every two to four years. At the same time many have courted federal and postal worker unions for their influence and financial help at fund-raisers and for travel funds and forums.

If government workers get de-Hatched, and become active in politics, some politicians might have to change their tune toward bureaucrats, who could become a major force in elections from the court house to the White House.