Marian L. Greenblatt, the combative member of the Montgomery County Board of Education who is being challenged for the Republican nomination to Congress by Elizabeth Spencer, a colleague on the school board, also has come under attack from county Jewish leaders because of her accusation that incumbent Democrat Rep. Michael D. Barnes indirectly supports the Palestine Liberation Organization.

Barnes' campaign staffers are preparing a full-page advertisement for the upcoming edition of the Jewish Week newspaper that is expected to bear the names of hundreds of Jewish community leaders and citizens repudiating Greenblatt's accusations that by being an advocate for revolutionary groups in Central America, Barnes supports the PLO.

The advertisement will appear in the same newspaper that two weeks ago criticized Greenblatt, who is Jewish, in an unusual signed editorial calling her accusation "as flimsy as it is misleading."

"We're going to have a substantial number of names" for the advertisement, said Barnes' campaign manager, Marie Garber. "If we had additional days to go on, we could have a thousand."

Greenblatt's accusation dogged the opening weeks of her candidacy, overshadowing her central campaign theme that on economic issues, Barnes is too liberal for Montgomery. It was almost an aside when, in a move to portray herself as a dearer friend of Israel than Barnes, Greenblatt called the incumbent "an advocate for the guerrillas" in Central America who receive aid and training from the PLO. Therefore, Greenblatt said, Barnes is supporting the PLO.

Barnes has called the accusations "unbelievable." A spokesman for the American Israel Public Relations Committee, the pro-Israel domestic lobby, called it "an unfair claim" and called Barnes a friend in Congress. Hyman Bookbinder of the American Jewish Committee called the charges "unfathomable." Norman Gelman, executive board member of the Jewish Community Council, called the accusation "somewhere between outrageous and hilariously laughable."

Greenblatt's statement was an obvious play for Jewish votes and funds in a county where 20 percent of the voters are Jewish. Instead of money and support, the unexpectedly harsh barrage of criticism left many Republicans privately questioning whether Greenblatt's strident style would prove too controversial for a county with a tradition of rejecting strident candidates and negative campaigns.

Several Republicans compared her campaign opening to that of former Rep. Newton Steers, who in 1980 launched his unsuccessful comeback try with a series of television advertisements perceived as negative, personal attacks on Barnes.

"To win in Montgomery County, you've got to attack the record," one GOP official said. "What Marian has done is attack Mike Barnes the person and she really did not get across the point she was trying to make."

Democratic party chairman Stanton J. Gildenhorn said he savors the thought of making Greenblatt's outspoken style the central campaign issue. "Mike Barnes is not a strident individual," Gildenhorn said. "Marian Greenblatt by contrast is the most unpopular individual in Montgomery County. She simply is too strident an individual to be accepted by this electorate."

Some Republicans believe that school board member Spencer would be the stronger candidate against the unassuming, professorial Barnes, who has been described as a congressional wallflower with all the dynamism of an algebra teacher. Spencer, who will announce her candidacy Tuesday on the courthouse steps in Rockville, is more moderate than Greenblatt in both her politics and campaign style. "Elizabeth Spencer fits that mold much better than Marian Greenblatt," said one high-ranking GOP official.

Despite the uproar, there has been no contrition from Greenblatt. Far from retreating on the accusations, she issued another statement accusing Barnes of "sending signals of support and lending legitimacy to guerilla movements" and encouraging "the clearly documented partnership of terror forged between the Marxist-Leninist guerrillas in Central America and the Palestine Liberation Organization."

Attached to the statement were four pages of newspaper excerpts, and quotations from PLO chief Yasser Arafat and El Salvador Communist party head Shafik Handal, who have expressed solidarity with each others' revolutionary goals. The attachments also included a statement from former Nicaraguan junta member Alfonso Robelo calling Barnes "the Sandinistas' best friend in Washington at present."

Greenblatt campaign manager James Teese said the candidate's opening day statements had been taken out of context. The subsequent statement and quotations were intended to provide that context, and the documentation, for the accusation, he said.

Teese, echoing the theme of several county Republicans, said the outcry of Jewish leaders really points out the close relationship between Jewish organizations and the county's Democratic party. "The leadership of most of the Jewish organizations is composed of Democrats and they are very liberal," Teese said.

During her six years on the school board, Greenblatt often has been in disputes with most of the county's organized Jewish groups. One came over her successful move to abolish a black culture class for teachers. A spokesman for the Jewish Community Council testified against the proposal, which led to a near-shouting match with Greenblatt, one participant recalled. "That began one of a series of flare-ups which continues until the present time," this Jewish community leader said.

At a spring rally for the annual United Jewish Appeal walkathon at the Washington Monument, Greenblatt was the only one of a group of Jewish elected officials who was booed when introduced, according to several participants. One official standing nearby called it "embarrassing." Teese said he had not heard about it, but added, "In a large crowd, if two people didn't like the fact that their school was closed, who knows?"

One Greenblatt supporter with close ties to the Jewish community said part of Greenblatt's strategy "has got to be to make an end run around Jewish leaders -- maybe even pointing out the interlocking relationship (with Democrats) -- and make her appeal directly to Jewish voters. And if she's going to Jewish leaders for fundraising, that's totally a brick wall."

Election returns show that in her most recent nonpartisan school board race in 1980, Greenblatt did well in precincts with high concentrations of Jews -- such as the Kemp Mill area near Wheaton, and the Blair House senior citizens project.