Spurred by deepening suspicion of one another and expectations of a razor-close contest, campaign organizers for the three major mayoral candidates in Tuesday's Democratic primary here are marshaling an unusual array of lawyers, monitors, statisticains and computer experts to spot possible election irregularities.

Drivers for candidate Sterling Tucker plan to follow D.C. Board of Elections and Ethics rental trucks that will transport ballot boxes from outlaying precincts to the city's central counting room at the Martin Luther King Library.

Security organizers for candidate Marion Barry have asked several computer experts to observe a demonstration scheduled today of the elections board's ballot-counting procedures involving electronic tabulators and the city's huge SHARE computer.

Hundreds of poll watches for Barry, Tucker and incumbent Walter E. Washington are being readied for deployment to the 137 precincts in the city. Teams of lawyers will be on hand in all three campaign headquarters from poll watches.

A special hotline is being set up at Washington campaign headquarters for immediate access to lawyers from outlaying precincts. Attorneys in the Tucker campaign say they have drawn up injunction papers so they can rush into court to stop the ballot count if they receive a report of fraud or other irregularity.

A Barry supporter has brought in a consultant from Chicago to instruct poll watchers how to spot election irregularities. Tucker forces have asked statistician and veteran D.C. election watcher Al Gollin, now living in New York, to be on hand for Tuesday night's ballot count.

The U.S. Labor Party, a smaller party running candidate Susan Pennington for mayor, has asked Mayor Washington to require voters to verify their identification when they go to the polls Tuesday to prevent possible multiple voting by individual residents. Voters are not required currently to show identification when voting.

"The paranoia level is running higher than usual this time," says Mary S. Rodgers, harried elections administrator for the elections board. She says she has been besieged with calls from various campaign offices with questions about poll watching and ballot security.

Campaign organizers and elections officials alike say they have no specific evidence of intended fraud in Tuesday's primary. But they say polls showing Tucker and Washington almost neck and neck, with Barry running a few percentage points behind, have triggered a kind of "close-election fever" that itself has created a general atmosphere of doubt, suspicion and temptation.

The temptation to "cheat a little here and there" is great in a close election, says elections board general counsel Winfred Mundle, especially by "over-zealous" individual campaign workers acting on their own initiative without the knowledge or approval of their campaign organization.

"Here you have an election," Mundle said, "where two of the (major) candidates are spending more than half a million dollars and will win up to 60 percent of the vote - and still lose. There's a lot at stake. There's a lot of power in that."

Tuesday's election may be the kind of cliff-hanger in which every write-in ballot, every challenged ballot and every late-arriving absence ballot could be crucial to victory.

"Those are the ones we're going to be watching especially carefully," said Barry campaign security chief Phil Ogilvie.

In addition to vague fears of election fraud, some campaign organizers are concerned about the possibility of tabulation errors and other mistakes by the board of elections, which in the past has been plagued by delays, internal tabulation discrepancies and on one occasion the temporary loss of a ballot box from the back of a delivery truck.

Procedures have been tightened in the last two years with the appointment of Mary Rodgers as chief administrator, however. Even Al Gollin, one of the elections board's severest critics in the past, now says city elections "are about as smooth as can be expected."

Rodgers will be chief of the election operation Tuesday and commander of the 1,200 "intermittent" or temporary employes hired to man the city's 137 precincts and count and sort ballots at the central counting room in the King library basement.

Voters in seven of the city's eight wards will mark paper ballots and place them in cardboard ballot boxes as they have in the past. In central city Ward 1, however, each of the 17 precincts will have an electronic ballot-counting machine, called Valtec, instead of a ballot box.

Ballots will be fed into the Valtec machine, which will automatically tabulate the votes for each candidate and should produce instant totals at the close of the polls. Polls will be open from 7 a.m. to 8 p.m.

Ballot boxes in the other seven wards will be sealed and brought to the central counting room by a fleet of 20 Avis rental vans, each driven by a Department of Environmental Services employe who will be accompanied by a D.C. police officer, Rodgers said.

At the central counting room, the wards will be divided by ward and the ballots fed into 18 more Valtec machines. Tally sheets containing precinct totals from the Valtecs will then be given to a crew of key punch operators who will punch the numerical totals into a bank of key-punch card machines. The resulting punch cards will be taken by truck to the basement of the Municipal Center a few blocks away at 300 Indiana Ave. NW and fed into the city's SHARE computer, where a final printout of city-wide totals will be produced. Rogers said that a preliminary total should be available by about 1 a.m. Wednesday.

Absentee ballots will be counted a week later on Sept. 19, Rodgers said. A week's lead time is needed, she said, so that elections board workers can verify that the absentee voter is registered and had not voted in person on election day.

Both the election and ballot counting procedures are similar to those of 1976, Rodgers said, and the same security measures will be used to protect ballots from tampering.

Some campaign organizers have grumbled that there may be weak points in the security through which opponents could gain access to ballots to premark them prior to their distribution to the precincts Tuesday. They said they also were concerned that ballots could be altered at some later time or fed through the Valtec counters two or more times.

Harley Daniels, key strategist and general counsel for the Tucker campaign, noted that DES employes will be driving the Avis rental trucks delivering the ballot boxes "and they're Washington men," a reference to the fact that the union representing city trash truck and other DES employes endorsed Washington for reelection.

"We'll be following each truck Tuesday night to make sure not one (ballot) box leaves the sight of our campaign workers," Daniels said.

Tom McAvoy, board member of a Chicago-based group called Project LEAP (for Legal Elections in All Precincts), warned of the possibility of "premarked) ballots here and helped set up a workshop scheduled tomorrow at 7:30 p.m. in Purity Baptist Church, 13th Street and Maryland Avenue NE, to teach poll watchers how to detect election irregularities.

McAvoy claims to have helped prevent voter fraud in Chicago and East St. Louis, and a steering committee has been formed to organize a permanent LEAP chapter here. Rolin Sidwell, temporary chairman of the local committee and an active Barry supporter, says the LEAP effort is non-partisan and he invited McAvoy to Washington on his own initiative, paying for McAvoy's expenses without the backing of the Barry campaign.

The Greater Washington chapter of Americans for Democratic Action also endorsed the LEAP project here but offered no money to McAvoy.

McAvoy, in a letter to candidates and their campaign managers, said there is a "potential for vote fraud and irregularities" here.

If preventive stripes are not taken and "significant iregularities" occur, he said, it could trigger adverse reaction in state legislatures where District officials are seeking ratification of the city's congressional representation amendment to the Constitution.

Rodgers of the elections board said there is little chance for ballot tampering. Unmarked ballots, which arrived yesterday from the printer, are currently stored in a "locked room in a locked building with an armed guard 24 hours a day," she said. She would not specify the building.

When the ballots are distributed to the precincts early Tuesday morning, poll watchers representing the various candidates "will be free to enter the precinct with the precinct captain at 6:30 a.m. and witness the opening of the ballots."

This should allay fears, she said, that precinct captains or workers loyal to one candidate or another might attempt to premark ballots before the polls open at 7. a.m.

Polls watchers also may check the ballot box at each precinct and shake it to see that it is empty before the precinct captain removes the seal from the ballot slot, Rodgers said.

As for the pickup of ballot boxes by DES drivers, all drivers will be accompanied by a police officer, minimizing the opportunities for tampering, she said.

District government guards will be present throughout the basement of the King library for the ballot counting, she said. All counted ballots will be removed immediately from the counting area, sealed and "stacked against a wall with an armed guard," Rodgers said, minimizing the chance of ballots bring re-counted either purposely or accidentally.

Rodgers acknowledged two potential weaknesses: lack of an identification requirement for voters entering the precinct polling places, and the so-called "postcard registration" process that permits an individual resident to register several times by mail, using different names and addresses.

"I hate postcard registration with a purple passion," she said. "It makes accountability very hard."

Voters identification has not been required, she said, because many residents, particularly older people, often have inadequate forms of identification. Besides, she said, "a lot of my precinct captains have been at their jobs a long time. They live in the community. They know the people and could tell if any strangers came in to vote."

Until the 1968 presidential election, signature cards of registered voters on file at the elections board central office were carried to precincts on election day so that precinct workers could verify voters by signature comparison.

That practice was stopped, Rodgers said, because the board felt there was unjustified "peril in transporting original documents across the city." Besides, she said, "our workers are not signature comparison experts. Also, lots of peoples' handwritingcan change from year, especially people who have had a stroke."