Timothy O'Shea unveiled a two-pronged strategy at a recent Montgomery County school board candidates' forum. First he attacked the two conservative incumbents, who happened to be sitting at opposite ends of the table, for their role in the recent school closings. Then he warned that the four liberals at his left would be in debt to those who favored a return to less structured ways of education.

That maneuvering, finessed in about three minutes, landed O'Shea and his running mate, Barry Klein, right where they wanted to be: smack in the middle.

At forums and in their literature, Klein and O'Shea rail against the current conservative majority, capitalizing on what they perceive as widespread dissatisfaction with the board's handling of school closings. On the other hand, they seek to link the four members of the Education Political Action Committee (EDPAC) slate with the liberal educational policies of the school boards of the early and mid-70s.

"We're moderates and the others are conservatives and liberals, it's as simple as that," said 47-year-old O'Shea, an international trade representative for Westinghouse Electric Corp.

"Philosophically, I agree with the conservatives' programs. But their attitude and approach have been wrong," added Klein, a 40-year-old Potomac physicist. "On the other hand, I can only judge EDPAC by its supporters and founders . . . [which includes] the very same [former] school board members who supported open classrooms and had a rather loose attitude toward discipline."

One of the cornerstones of their campaign is a 38-point academic agenda. But Klein and O'Shea, a Gaithersburg resident, have run into some problems making it a major issue because nearly all the other candidates support the same ideas. They want an extra year of science, so do EDPAC candidates; they would lobby the County Council for more money for the lower Silver Spring area, EDPAC candidates make the same argument. They support the mandatory final exams and homework policy instituted by the present board, but say the policy is too stringent; EDPAC candidates would leave the hours and specifics up to the individual teacher.

EDPAC was formed about a year ago to oust the conservative board majority and as recently as June, both Klein and O'Shea sought its endorsement.

Until last month's primary, most of their campaign was aimed at incumbent conservatives Carol Wallace and Joseph Barse and the actions of the current board majority.

Tactics changed swiftly after the EDPAC candidates captured the first four positions in the primary while Klein and O'Shea squeaked through with the last two qualifying spots among eight nominees. Perhaps more importantly to Klein and O'Shea were the fifth- and sixth-place finishes of Barse and Wallace and the positioning of Barse's two conservative running mates, Herbert Grossman and Elizabeth Witzgall, in the ninth and tenth spots in the field of 15, barely missing a spot on the Nov. 2 ballot.

The message of those results -- that there still is a conservative, or at least moderate, vote to court -- was not lost on O'Shea and Klein.

Since then, Klein, who ran independently in 1978 and finished fifth, just missing one of the four seats, and O'Shea have considerably toned down their attacks on the board, limiting criticism specifically to school closings.

They now are aiming salvos primarily at the EDPAC candidates, attacking them for concentrating their campaign on communities where schools were closed, and for contributing to a growing partisan (Democratic) tinge to the school board elections. A vote for EDPAC, they charge, is a vote for another four years of divisiveness.

Two weeks ago Klein and O'Shea, after a press conference by board member Marian Greenblatt, conferred with conservative board members Eleanor Zappone and Suzanne Peyser about how they would vote if they were on the board.

That led to speculation that the two might hook up with Barse and Wallace. Although not actively campaigning for Klein and O'Shea, a number of board members, including Barse, are openly saying they would welcome the election of the two along with Barse and Wallace.

"It became clear to us during the primary campaign that what people were angry about was not the current board's educational philosophy, but their approach to school closings," explained Klein. Klein said he and O'Shea had decided not to link up with Barse and Wallace, but welcome their support.

Even if Klein and O'Shea don't win, their middle-of-the-road campaign could dilute EDPAC's strength and result in the reelection of either Barse or Wallace, or both. To prevent EDPAC candidates from gaining control of the seven-member board, the conservative majority must limit EDPAC candidates to two seats.

Returning board member Blair Ewing, the lone liberal in the present alignment, would likely form a new majority if EDPAC candidates win at least three seats. The four EDPAC candidates are James Cronin, Marilyn Praisner, Odessa Shannon and Robert Shoenberg.

"It surprises me that they Klein and O'Shea seem to be saying there is a difference between us. At most, there are only minor differences," said EDPAC candidate Praisner, who finished first in the primary voting. "I guess it's a smart political strategy, but I think they're grasping at straws."