Each time Glen Saluter maneuvers his blue pickup truck into the vast, crowded parking lot of the Defense Mapping Agency in Brookmont, he is reminded why he regrets his vote for Jimmy Carter in 1976.

Thanks to the president, Saluter has to pay for a parking space.

The Carter administration's paid-parking program for federal workers undoubtedly pleased taxpayers around the country who constantly grumble about the bloated and inflation-proof federal work force.

But Saluter, like most of the 2,000 employes at this federal installation just across the Montgomery County line, has been seething for months over the $120 he pays each year for parking in a suburban neighborhood where mass transit is scarce and where other workers -- including those at the shopping center across the street -- park for free.

"It's definitely changed my vote," Saluter says. "First Carter forced us to start carpooling, and now he's charging us for parking in a place where there's no mass transit."

Saluter is not the only federal worker who counts his parking fees as a swing factor in his choice for president this year. In fact, it is on such issues, largely unnoticed by the general public but paramount to federal workers, that a large percentage of the vote in suburban Maryland may hinge on the May 13 Democratic primary.

This past week, for example, some 15,000 federal workers and retirees in the local area responded to a questionnaire by Washington Post columnist Mike Causey on the issue of merging federal retirement and social security benefits, and said overwhelmingly that they would vote against Carte if he supports the move. [Details, page B2.]

In Montgomery County, nearly 60,000 potential voters -- more than 20 percent of the adult population -- judge Carter as a boss as well as a president, and thousands more depend on him to manage their benefits as federal retirees.

However, they may judge him as a president, a solid majority of these workers -- particularly in the lower pay grades -- seem to believe Carter has been an unfair, vindictive employer whose policy has been to attack their work, their pay and their benefits at every turn.

Even those who don't particularly like Carter's political competitor, Sen. EDWARD M. Kennedy, are determined to send the president a message. "There's going to be a strong mutual encouragement to give this guy a kick in the ass," said Bill Colligan, a union official and oceanographer at Defense Mapping.

"There's has always been this high-handed, 'screw 'em' attitude by this administration toward the federal worker. We feel ignored and dumped on."

Political observers in Montgomery, where federal employes are courted as aggressively by county candidates as they are ignored in other areas, agree that the federal worker vote could help Kennedy overcome Carter's potent support from the business community -- which has contributed more than $150,000 to his campaign -- and from the county's Democratic activists, who are largely committed to him.

Federal employe issues are likely to be more of a litmus test in 1980 then they were in previous elections, and it's an unquestionable negative for Carter," said Keith Haller, who managed U.S. Rep. Michael Barnes' 1978 campaign in Montgomery County. "The federal employes feel this is a turning point for them, that they have to make themselves noticed."

Virtually every effort the Carter administration has made to improve the federal bureacracy and curtail enpenses and inefficiency in civil service has offended rank-and-file federal workers. "I've never heard such strong negative expressions about a president as I have about Carter," said Dan Jaspan, whose Silver Spring organization of retired federal workers now refers to the rosier era before Carter's anti-bureaucratic platform as "B.C."

Among Carter policies that may change federal workers votes:

Pay reform. Carter has proposed a reorganization of civil service wages that would save the federal government $3 billion annually, but would reduce the scales and salaries of many local workers. He has also included a raise of 5.5 percent for federal employees in next year's budget -- far below the 11 percent they have asked.

Retirement benefits. Carter would like to reduce the number of cost-of-living raises for retired workers from two to one per year. Many union leaders also fear he will eventually support a plan under consideration by Congress to merge the federal retirement system with the social security system, thus reducing federal pensions.

Agency cutbacks. Carter's balanced budget would mean a loss of jobs for federal employes. Already they are angry over the increasing practice of contracting out federal services, and postal workers fear that Saturday mail service may be discontinued. Many workers are still upset over the 1978 civil service reform that downgraded some jobs and made firings easier.

Beyond the specific issues, of course, federal workers have always bristled at Carter's anti-Washington rhetoric. "Most of us who have been in the federal government for 20 years or so have seen stuff come at us in all kinds of ways," said Colligan. "It's the way Carter does it -- it's this stereotype of the federal employe sloshing at the public through -- that's offensive."

Kennedy has distanced himself from Carter on several of the federal workers' test issues, and his supporters both in Montgomery County and on the state level plan to promote the differences in coming weeks.

According to staffers, Kennedy is "skeptical" of Carter's pay reform proposals, opposes parking charges at federal installations in suburban areas like Montgomery, and probably will be opposed to reducing the number of cost-of-living increases for retirees.

But like voters in other areas, many of the federal workers in Montgomery County are not attracted to Kennedy, only angry at Carter. Some perceive their prospective votes for Kennedy as protests that are only made more appropriate by the unlikelihood, in their view, that Kennedy will win either the state or the party nomination.

"Kennedy has a number of things going against him," said Donald McIntyre, head of the American Federation of Government Employees' 14th district, which includes suburban Maryland. "I think federal workers are looking for someone other than Carter but they are not necessarily turning to Kennedy."

"I feel that unless something unusual happens, President Carter will get the nomination," said Leo Doherty, who heads the postal workers' union local in Silver Spring. "But the overwhelming feeling is that we are extremely upset about what's happening, and if the votes come out, Carter will get the message."