Ollie-mania has come to Fairfax County politics.

"Maybe you can't go to Nicaragua," declares a flier making the rounds of county high schools and colleges, "but you can help by joining Students for Herrity!!"

Above that message, a photo of the crew-cut marine lieutenant colonel who became a household television image during the recent Iran-contra hearings appears with the bold-type caption: "Oliver North, commitment."

That's not the only poster that uses the allure of military adventure on behalf of John F. Herrity, the Republican county board chairman in Fairfax who is seeking reelection Nov. 3.

Another flier depicts a camouflage-clad, Rambo-like soldier, and urges students to "join the winning team" and work as volunteers for Herrity.

A third flier depicts a $10 bill and three quarters, accompanied by the message: "It pays to work for Jack Herrity." According to a Herrity campaign spokesman, the remuneration for students is "in fun" -- not hard currency.

Herrity, seeking his fourth term as the county's top elected official, is being challenged by Democratic Supervisor Audrey Moore of Annandale.

Both candidates have tried to enlist student volunteers to help with clerical work, literature drops and the like, but the Herrity camp's appeal appears to have been more successful. At a candidates' forum last month at Robinson High School, Herrity enlisted 130 student volunteers -- nearly twice as many students as Moore.

One reason for the students' zeal is that some Fairfax County public schools give academic credit in their government classes for volunteer work in political campaigns.

Tom Herrity, the chairman's son and campaign manager, said the Herrity fliers are designed "to attract attention.

"You use whatever's been an issue lately," he said of the North campaign pitch.

"We are proud of our youth movement and we stand by it."

County Democrats are increasingly confident that they will capture the county board chairmanship, and some are laying the groundwork for what they expect will be a Moore administration.

According to several leading developers and business leaders, state Sen. Richard L. Saslaw, a Springfield Democrat, has been trying to build bridges on Moore's behalf with key members of the private sector.

Moore has been a leading critic of developers since she was elected to the board in 1971. As a result, business people in the county are for the most part united behind Herrity and deeply suspicious of Moore.

Enter Saslaw, the self-appointed Democratic emissary to big business.

"There's just a big misconception by the people at Tysons Corner," he said in an interview. "I just tell them that I don't think they have as much to fear as they believe and they ought to give the woman a chance. Assuming she wins the election, which I think she will, I think it'll be good for her ultimately to meet with these people."

According to some developers, however, it is unlikely that Saslaw can do much to dissolve attitudes toward Moore that have hardened during more than a decade.

It is an old tactic in politics to raise age as an issue whenever one's opponent has reached or passed retirement age. Along with ringing pronouncements that it is time for "new blood" come suggestions that the aging candidate has "slowed down," "lacks stamina" or may be quite ill.

In Fairfax's Centreville District, where Republican Linda Douglas, 42, is challenging Democratic Supervisor Martha V. Pennino, 69, some Republicans have launched a vigorous whispering campaign to spread the notion that Pennino is no longer up to the job.

In conversations with reporters, Fairfax GOP officials regularly go off the record to worry aloud about Pennino's health and to suggest that she should have retired rather than seek reelection.

Pennino, elected to the board in 1967 and now its vice chairman, is widely known as "Mother Fairfax."

It is true that she enjoys going to the beach during the board's summer recess. It is true that her voice quavers -- and has for many years. And it is true that she had a relatively common -- and apparently successful -- operation for cancer three years ago.

Pennino's colleagues, not to mention reporters who cover the county Board of Supervisors, say there is nothing to indicate that she is slowing down. Her attendance record is better than some board members' and not as good as others'. She has never missed a board meeting because of health problems. She is physically active, even vigorous. One board Republican who is three decades her junior speaks admiringly about Pennino's tennis game.

"Martha's health is fine," said one high-ranking county official.

"But all's fair in politics, and I suppose it's natural that her opponents would try to raise questions about her."

Douglas acknowledged that "a lot of people talk about it," but insisted that she does not. "I don't think that age is the issue," she said. "The issue is who can best lead the district."

Douglas has said in public forums that Pennino lacks energy and commitment to her job -- an assertion that Pennino disputes.