Members of Congress representing 1.2 million jittery taxpayer-voters (who get their paychecks from Uncle Sam) are forming a task force to monitor the Reagan administration's plans to cut back federal programs and whack jobs.

Coalition members come in all racial, ethnic, regional and political hues. But they have a couple of things in common. They are politicians who would like to keep getting reelected, and they represent people who make up 42 percent of the federal work force from states and congressional districts where feds are a major political force. Legislators are most anxious that their constituents, who pump millions of dollars into hometown economies, don't wind up on welfare or in unemployment lines.

Object of the Federal Government Service Task Force: to serve as an information network on issues -- jobs, retirement, reorganization -- of interest to U.S. workers, and to advise key members of Congress that they represent lots of federal and postal employes. Staff director Robert Honig says at least 75 House members come from districts with 20,000 or more federal workers. The typical congressional district has 500,000 people -- men, women and children -- so a voting bloc of 20,000 or more is something to consider every other November.

Rep. Mike Barnes (D-Md.) chairs the group, which includes Reps. Vic Fazio (D-Calif.), Barbara Mikulski (D-Md.), Stan Parris and Frank ywolf (R-Va.), Tom Lantos (D-Calif.), Morris Udall (D-Ariz.), William H. Gray (D-Pa.), Roy Dyson (D-Md.), Robert Matsui (D-Calif.), Norman Dicks (D-Wash.), Robert Roe (D-N.J.), Julian Dixon (R-Calif.), Glenn Anderson (D-Ill.), Edward J. Derwinski (R-Ill.), Benjamin Gillman (R-N.Y.); Thomas Bliley (R-Va.), Marjorie Holt (R-Md.), William Whitehurst (R-Va.), and Tony Coelho (D-Calif.). Other members are D.C. delegate Walter Fauntroy, and resident commissioners A. B. Won Pat of Guam and Baltasar Corrada of Puerto Rico.

The Task Force will begin a Senate recruiting drive today. (Sen. John Warner (R-Va.) is the only member so far.) Pamphlets explaining the importance of the federal-postal-retiree population in each state will go to the 99 nonmembers in the Senate, and they should open some eyes. Consider some numbers:

Alabama has 60,000 federal workers and 25,000 civilian federal retirees. . . California, more than 290,000 federal workers and 138,000 government retirees. . . Florida, 80,000 feds and 86,000 retirees. . . Illinois, 101,000 U.S. workers and 35,000 retirees. . . Maryland, 131,000 workers and 50,000 retirees. . . Virginia, 144,000 workers, 66,000 retirees. . . District of Columbia, 207,000 workers, 42,500 U.S. retirees. . . Michigan, 54,000 and 13,000. . . Missouri, 64,000 workers, 25,000 retirees. . . New York, 157,000 feds and 63,000 retirees. . . New Jersey, 68,700 feds and 30,000 retirees. . . Washington State, 61,000 U.S. employes and 33,000 retirees. . . West Virginia, 15,800 feds and 6,400 retirees. . . Pennsylvania, 126,000 U.S. workers and 44,000 retirees. . . Massachusetts, 56,000 feds and 30,000 retirees, and Texas, 148,000 federal workers, and 66,400 retirees.

Task Force members hope to come up with proposals that would spare the twice-yearly cost-of-living raisesthat federal, postal and military retirees get.President Reagan has proposed cutting retirees back to one inflation adjustment each year. They plan to work closely with the Senate Governmental Affairs Committee and the House Post Office-Civil Service Committee, which have jurisdiction over most federal-postal employe matters.

Staff director Honig says the task force hopes to convince Congress that it doesn't make sense to beat bureaucrats on the head and then expect them to go joyfully about their important business. Politicians sometimes forget that feds are people too, that they have the same dislike of red tape and waste as other taxpayers.