Union leaders who predict President Reagan will dismantle the government and force bureaucrats into bread lines and making the same sort of mistake they did in 1976 when they hailed President-elect Carter as the savior of the Civil Service. Then, as now, the union chiefs seem to be guilty of rhetorical overkill.

Carter, as the optimists said he would, did some good things for government.

And he made attempts to re-engineer agencies to make them more "responsive" and efficient. He also did some bad things, from the standpoint of people in government. He did both as did Nixon and Johnson and Ford. So no doubt, will Ronald Reagan.

After helping -- they believe -- Carter defeat Ford in the 1976 squeaker, many federal union leaders spent the next four years kicking the stuffing out of him. The man they loved, they said, became the ruthless kicker of bureacrats, the rapist of the merit system, the muzzler of the whistleblowers, and the biggest fibber since Pinocchio. Now that they have lost Carter, there is mourning in some union offices. To which the Carter people reply, "Where were you when we needed you?"

At major federal and postal union conventions last summer, delegates -- generally savvy, rank-and-file local leaders -- instructed their national officers not to endorse Carter or Reagan. One got the feeling that if James K. Polk were around, most members would have picked him over the available choices.

Union leaders blasted Carter for failing to push for changes in the Hatch (no politics) Act, like he promised; for vetoing a shorter work week for federal firefighters after he allegedly promised the union's president that he would sign it into law; for his "reform" of the Civil Service system; for failing to back the whistleblower protection unit he set up; for instituting pay parking for federal workers, and for going back on promises to protect jobs in the postal service. They raged because the president proposed cutting out one of the two cost-of-living raises U.S. military and federal retirees get annually, for even thinking about merging the government retirement system with Social Security, etc., etc.

It was only in the last week of the campaign that the executive board of the giant American Postal Workers Union endorsed Carter. The leadership of the American Federation of Government Employees did not endorse him, although White House officials were eager to get that union label, especially in Texas, California, Florida and metro Washington where AFGE has a big membership. But while the unions warned their members of the evils of a Reagan administration, the Carter people say that the big outfits sat on their hands, for the most part, or came in with help that was too little and too late.

One union that did endorse Reagan, the Professional Air Traffic Controllers Organization, says the president-elect has promised that controllers will be exempt from any hiring freeze he puts on government. The National Association of Retired Federal Employees, meanwhile, got a pledge from Reagan to maintain the twice yearly COL raises.

Most government unions concentrated their time, talent, staff and money on congressional races. And they don't like what they got in return. The day after the election, AFGE President Kenneth Blaylock issued a statement that said, in part: "The only winners in yesterday's election were the forces of fear and reaction. Clearly, the electorate responded to the negative appeals -- fear, doubt and uncertainty. The appeal of the billion-dollar corporate blitz that dominated the media, the negative zeal of groups like the Moral Majority and othes have badly damaged the American electoral process.Instead of picking candidates who offer constructive solutions to problems, American voters seemed to fall prey to the strident zealots who dominated the entire campaign . . . ."

Months ago, Alan K. Campbell, the political scientist who heads the Office of Personnel Management, said that despite their differences with the White House, federal workers and unions would have to support Carter "or get Reagan" by default. There may have been a clue that would happen when the AFGE took a straw vote in October. The preelection issue of the union newspaper, which goes to nearly 300,000 members, asked members who they wanted for president. The results, announced Oct. 29, showed that 46 percent liked Carter, 33 percent, Reagan; 11 percent, Anderson; and 10 percent, "other" candidates.