It was going to be a rousing election-eve send-off to the Carter campaign in Maryland: Robert Strauss, Gov. Harry Hughes and 500 Democrats in the front yard of Montgomery County Executive Charles Gilchrist's Rockville home.

Strauss -- Carter's national campaign manager -- Hughes and a few other officeholders dutifully showed up yesterday afternoon, but only 150 or so Carter supporters came to see them. And some of these said they preferred gardening to another late-season primary.

That ho-hum attitude in a politically active and aware corner of the state reflects, as much as anyting, the lack of interest both Republicans and Democratic voters in Maryland have shown in this Tuesday's presidential primary. By and large, according to campaign officials across the state, the candidates are being ignored.

"We're trying to stimulate some interest, but it's difficult to do," said State Sen. Harry J. McGuirk, who is trying to get out votes for Carter in his South Baltimore district. "There's been nothing that's happened, no chain effect to get everybody active."

Some organizers attribute this prevaling lassitude to party activists' disenchantment with the four available primary candidates: Carter and Edward M. Kennedy on the Democratic side and Ronald Reagan and George Bush for the Republicans.

But others point to the voter feeling that the national nomination contests were already over this year before Maryland voters could have their say.

In fact, Bush and Kennedy, the two candidates to whom the Maryland primary is most important, have spent much of their time trying to convince voters in Maryland that they still have a chance of winning their parties' nominations.

And supporters of Carter and Reagan have tried to win votes by taking the opposite tack. "There's no doubt in my mind that President Carter is going to be the nominee," said Gov. Hughes at Gilchrist's rally yesterday. "So let's have Maryland be in the win column and not make the mistake we did four years ago," when Maryland Democratics supported California Gov. Jerry Brown.

"People are beginning to think it's over and why not rally behind the guy who's going to win," said Donald Devine, the University of Maryland political science professor who serves as Reagan's regional chairman in Maryland.

The very lack of enthusiasm is "just fine," he said. "That's what we want . . . Nice, calm, normal movement toward the nomination.

It's the Bush campaign and the Kennedy camp that really need to have the blood rolling around," he said.

For those two campaigns, Maryland is seen as one of the principal links between the Pennsylvania primary three weeks ago and the crucial votes of June 3, when voters in California, Ohio and New Jersey will probably make or break their dwindling chances for their parties' nominations.

Both campaigns are hoping that a victory in Maryland will offset their losses in three state primaries last week and provide a surge of momentum for the last three weeks of the primary campaign.

For Carter and Reagan, Maryland is an opportunity to further bolster their contentions that the nominating process is really already over by winning in a state where each man was defeated in the 1976 primary.

Neither frontrunner has made a major effort to win the state, partly because both are approaching federal spending limits. Carter's campaigners began intensive work in Maryland only days ago, and after an appearance last October, Reagan never visited the state, preferring to campaign elsewhere or rest at his home in California.

Maryland also holds little for the strategies of delegate-counting that Carter and Reagan have recently embraced. The 59 Democratic and 32 Republican delegates, because of apportionment rules, are likely to be split fairly evenly in both parties.

As the campaign entered its last three days, few were willing to predict winners in either party. Among Democrats, Carter was believed to be a slight favorite, with many voters undecided, while the Republican race was almost universally dubbed too close and too murky to call.

The low turnout expected Tuesday is attributable in part to the scarcity of closely contested state and local races in either party.

In the local area, the campaigns attracting the most attention have been the 12-way race for the Democratic nomination for the U.S. Senate seat held by Republican Charles McC. Mathias and the Republicans' and the four-candidate race in Montgomery County's 8th Congressional District for the right to oppose incumbent Democratic Rep. Michael Barnes.

In Baltimore, interest has focused on the campaigns of five incumbent judges and the Democratic primary in the 2nd Congressional District, where state Del. Thomas Kernan is challeging incumbent Rep. Clarence Long.

For Kennedy and Bush, losses in Maryland would be particularly painful not only because both targeted the state for a significant campaign effort, but because Marland is weighted with constituencies that could have been expected to support the two challengers.

By primary day, Kennedy planned to spend parts of six days in Maryland, and he has bought television time, for a new series of advertisements emphasing his theme that a president "can make a difference."

His Maryland campaign organization, led by Rep. Barbara Mikulsi of Baltimore and her staff, has targeted large blocks of voters around the state they believe can carry a Kennedy victory: Jewish voters in the "northwest corridor" of Baltimore City and Baltimore County, blacks in Baltimore City and Prince George's, ethnic Italians and Greeks and federal workers in the Washington suburbs.

Even among those voters, however, suport for Kennedy seems to be muted by disenchantment with his personal image, or even with the Democratic Party in general.

"Normally there might be a tremendous amount of emotion for a strong anti vote, an anti-Carter vote," said State Sen. Melvin Steinberg, who thinks "extreme complacency" reigns in his heavily Jewish Baltimore County district. "This year there's really no serious anti vote because Kennedy is not really viewed as a viable alternative."

A poll of 81 Jewish voters in the Baltimore area by the weekly newspaper Jewish Times last week supported Steinberg's argument. It showed more voters undecided than supporting either candidate.

Kennedy's Maryland campaign manager, Ernie Kessler, said yesterday he believes Kennedy is still trailing Carter statewide among voters who have made up their minds. "It's an uphill battle," he said. "The question is whether we can get to the top of the hill before primary day."

Kessler said Kennedy is "substantially behind" in Baltiore County, which normally delivers close to a quarter of the vote in Democratic primaries, and in the state's traditionally conservative rural areas.

Supporters of Kennedy say they must build up leads in Montgomery and Prince George's Counties, with the help of their traditionally liberal constituencies and federal workers, and win Baltimore City if they are to carry the state.

Carter appears strong in Maryland almost in spite of his campaign, which has been lackluster since its January endorsement by more than 300 of Maryland's elected officials, including Hughes and Baltimore Mayor William D. Schaefer.

Although Carter supporters have raised well over $400,000 in the state, Carter's coordinators have largely relied on those endorsements and a last-minute media and canvassing effort to carry them through the election.

Through spokesmen like Schaefer and Hughes, who spent three days stumping the state's rural extremities, the Carter campaign has emphasized Carter's aid to Baltimore and other urban areas and his integrity as a leader.

Now, Curt Wiley, Carter's state campaign manager, believes that with the help of a visit tomorrow by First Lady Rosalyn Carter and the distribution of 400,000 flyers, Carter can win Maryland by carrying the areas Kennedy's campaign has condeded, plus Baltimore.

"Baltimore City," Wiley said, "is going to be a close ballgame. I haven't seen anybody give numbers that shows either side with an edge there."

In an attempt to make voters feel their ballots still count, Bush spent two days in the state last week eating crabcakes and Italian pastries and telling every available voter, reporter and television camera that the race isn't over yet.

And while Bush trekked from Baltimore to Montgomery County and Prince George's County to Annapolis, Reagan sat at home in Los Angeles and his penurious state campaign methodically continued the business of telephoning voters to make their pitch and trying to blunt the impact of Bush's $50,000 last-week media campaing.

But while the Reagan campaign had barely enough money to keep its Wheaton campaign offices in operation, let alone to buy advertising time, a group called the Official Reagan Delegate Committee spent about $7,500 on radio ads that have been running on 20 stations around the state this week, according to Bill Neptune, one of the committee's organizers.

The advertising for Bush, which consists entirely of 30-second spots produced by the media advisers to the national campaign, is designed to catch the attention of voters in the populous Baltimore-Washington corridor, where Republicans tend to be moderate to liberal.

Particularly important for both the Reagan and Bush campaigns is Montgomery County, where more than one in five of the state's 419,000 Republicans live and where a sharply contested congressional primary is expected to draw many Republicans to the polls.

"It's going to be close," predicts state party chairman Allan Levey. "The key is Montgomery County. If George Bush does well and wins Montgomery County, he'll win the state. If he just breaks even, he'll lose the state."

Alread, Levey and most observers outside the two campaigns concede that Bush should carry the two congressional distrcits in Baltimore City.

Bush campaign organizers, however, find Levey's emphasis on Montgomery County simplistic. But a group of high school volunteers spent the weekend traveling around western Montgomery in auto carvans with their parents, distributing Bush literature and sample ballots.

And it is in Montgomery County, particularly, that the effect of John Anderson's name on the ballot may be felt. Anderson dropped out of the Republican race to run as an independent, but his decision came too late for his name to be removed from the Maryland ballot.

"Montgomery County would be the principal place Anderson would get votes, and he would take them from Bush," said J. Glenn Beall, Bush's state cochairman.

So Bush organizers are asking state elections board chairman Willard Morris to post signs at polling places informing voters that Anderson is no longer a Republican candidate. Thus far, Morris has refused.