State Sen. John J. Garrity (D-Prince George's) thought he finally had mastered the art of tactfully hearing out special interest lobbyists at the Maryland General Assembly while being able to ignore any pressure they might try to put on him to vote their way on the issue.

Garrity said his experience with lobbyists in his three years as a legislator did not fully prepare him for the high pressure campaign Maryland teachers employed this session in an effort to block legislation that would overhaul the outdated pension system for state employees.

In the past two months, he has been barraged by letters, telegrams, telephone calls and visits from scores of teachers in his district urging him to oppose the pension proposal and threatening that a wrong vote could cost their support in this fall's election.

Such warnings by citizen groups are not uncommon in an election year, but open threats by teachers are especially compelling for Garrity and his fellow legislators because, unlike other special interest, the teachers are a single-issue constituency that delivers on its promises.

"It's a helluva intimidating factor," said Garrity, who ended up sponsoring a compromise on the pension issue that passed the Senate. "There's tremendous pressure just to be down and play dead. You can't satisfy these people unless you always vote with them."

Garrity's recent experience illustrates the legislative tactics of the "teachers lobby," a tightly knit state-wide organization of educators that generally is regarded as among the most powerful and effective pressure at the Maryland General Assembly.

The teachers have ample sums of money to back up their lobbying efforts: this year their union plans to spend more than $140,000 on the full gamut of "legislative services." They also field a large contingent of six registrede lobbyists.

A legislative scorecard for the teachers' lobby compares favorably to any of the special interest groups here. Over the years, it has obtained one of the most generous teacher retirement plans in the nation, complete with cost-of-living increases for pensioners.

One of the nation's first collective bargaining laws for teachers was steady annual inceases in state aid to education has helped assure new teaching jobs. The lobby also has protected Teacher tenure rights and preserved local curriculum control.

One of its most sought after goals - an agency shop that could vastly enrich its treasury with new dues money - has yet to be acheived. But the group's battle for the concept has prompted some of the most hard fought and emotional legislative battles in past years.

The lobby's effectiveness lies in its numbers. It can trap tens of thousands of teachers throughout the state to fight for education and labor issues.

Behind the saturation mailings and the arguments of its lobbyists is a simple and meaningless message for legislators: today's pressure group can be turned into tomorrow's political organization. It is a message cultivated by MSTA leaders.

The association's real strength comes from the ability of its leaders to mobilize their troops for political campaigns. In an election year, the statewide network of teachers' groups becomes a potent force for a favored candidate.

They can decide the outcome of an election in many parts of the state. They canvas neighborhoods for friendly candidates, hold rallies and work the polls.Their state and local unions circulate newsletters with endorsements and contribute thousands of dollars to campaigns.

"The teachers can be the difference between victory and defeat for me," said Garrity. "The most important block would be the Irish in my district. Then the citizens of municipalities. And then the teachers. They have a very high yield of voter turnout on election day."

"I think they're pretty effective in putting bodies on the street," observed Sen. Arthur H. Helton Jr. (D-Harford). "If they're with you, they can give you a whole campaign organization. They can cover a county door-to-door and blitz an area with pamphlets."

The teachers lobby officially is represented here by the Maryland State Teachers Association (MSTA), the union for 37,000 teachers and teachers' aides throughout the state's 24 school districts. The union's $2 million annual budget is funded by membership dues.

MSTA serves as the vanguard for the lobbying and political activities of its scattered membership. As the administrative arm of the teachers' lobby, it helps shape legislative goals in advance of each session and formulates the strategy to achieve those goals.

The teachers' lobby fights for the economic interests of educators with at least as much ferocity as utility and insurance lobbyists who work for the profits of their stockholders. The classroom role of teachers gives them a special status in the eyes of many lawmakers here.

"Everyone has a natural respect for school teachers," remarked Sen. Victor L. Crawford (D-Montgomery). "Your kids spend more time in school with teachers than at home with their parents. These people aren't lobbying for higher interest rates. They're lobbying for education."

Every fall, MSTA hosts banquets in each of the state's legislative districts, brining together local teachers, community leaders and legislators to discuss teacher concerns for the coming session. Special awards often are given to law makers deemed to be "friends of education."

On most of the teacher-related issues at the legislature, MSTA representatives rely on the traditional forms of lobbying in state house halls and Annapolis night spots. They easily are identified by the small blue and white "MSTA" pins they wear in suit lapels.

Faced with more pressing issues, such as this session's pension reform proposal, the teacher's lobby goes into high gear, activating what MSTA officials like to call the strategy of "Mass involvement participation."

"We can call on people in every legislative district in the state and probably every precinct and ward," said Tom Gray II, MSTA's chief lobbyist. "These are people who are among the most educated and best informed in the community. It's a tremendous reserve of talent."

This session's pension battle provides a good view of MSTA's high powered tactics. It is a measure of the lobby's strength that the pension bill was almost killed in the Senate and only passed after its effective date was delayed 11 months. It still awaits consideration in the House of Delegates.

Shortly after the bill was introduced, MSTA sent letters to each member describing the pension proposal as "devastating" and urging the educators to "flood Annapolis with cards, letters, telegrams, telephone calls and visits . . . to help stop the legislative steamroller."

The union's biweekly newsletter kept up the pressure with regular articles critical of the pension proposal. Large yellow posters with large, black letters reading "Pension Alert" were sent to schools calling on teachers to contact their representives.

Teachers responded with thousands of pieces of mail and descended on Annapolis is buses and car pools from every county. They presented their legislators with petitions and lobbies them in state house offices and invited their lawmakers to dinner.

"This has been one of the toughest fights I've ever been in," said Sen. James Clark (D-Howard), who floor managed the pension bill. "Anybody who can get 30,000 people to mail a card to every delegate and senator has got to be the most powerful lobby in Annapolis."

The fight was made tougher by the election year concerns of many senators. "Good bill, bad year," was the rallying cry of several senators as they calculated the clout of teachers at the polls. It is a calculation encouraged by MSTA officials.

MSTA has a lot to offer in return. It's political arm, the Maryland Education political Action Committee will endorse state and local candidates and circulate its recommendations in newsletters to its members. The committee also will make campaign contributions to favorite candidates.

A profferssional political coordinator who works for MSTA will help organize campaigns of candidates "friendly to education." Local teachers can be enlisted as foot solders for campaigns, answering telephones, handing out campaign materials and addressing envelopes.

Because of their close contact with PTAs and parents, teachers can extend their influence beyond their ranks. "There is a great spill over," said Sen. Julian L. Lapides (D-Baltimore). "They know the newspaper man, the doctors and the lawyers through their kids."

The organization has one other advantage that other presure group in Annapolis has: MSTA can count among its ranks a powerful member of the House of Delegates - Frederick C. Rummage, who is chairman of the pro-teacher Prince George's County delegation as well as executive director of the Prince George's County Educators' Association (PGCEA).

An outspoken leader of the teachers' union at home and the man who bargains teachers' contracts, Rummage insists he is not swayed by his union affiliation in Annapolis and abstains from voting on union issues. But the PGCEA lobbyist finds a receptive audience in the county delegation.

The teachers' lobby has a special status among the special interests here. Even James J. Doyle Jr., the premier Annapolis lobbyist, speaks of them with envy. "There's more initial acceptance of teachers because of their noble calling," he said.

Some legislators see the teachers' lobbt in a different light. "They don't fool me," said Sen. John C. Coolahan (D-Baltimore County). "They're looking for wages and working conditions, the same as any special interest.They have a perfect right to do that. But when they throw in the children, that's when they get phony."