Rick Nelson, a soft-spoken chemistry teacher at Jefferson High School in Fairfax County, is preparing to take a temporary leave next month to become the Fairfax Education Association's (FEA) full-time adversary.

Nelson is the driving force behind the Fairfax County Federation of Teachers, which is beginning a push to rival the more popular FEA for membership and power. Nelson says the decision by the American Federation of Teachers to provide the funds that will allow him to devote all of his time to union organizing is one indication of how serious federation members are about challenging the larger FEA.

When Nelson began teaching in Fairfax 10 years ago, he was a member of the FEA, which is affiliated with the National Education Association. He became disenchanted with the association several years later and resigned his membership. In 1977, after the Virginia Supreme Court outlawed collective bargaining, Nelson gathered 135 other disgruntled teachers and formed the militant Fairfax County Federation of Teachers -- the local arm of the American Federation of Teachers and a member of the AFL-CIO.

Nearly 2 1/2 years since he founded the local, Nelson is enthusiastic about the future.

Nelson says that when he began teaching in Fairfax, a labor union would have found no support among Fairfax teachers -- "they didn't need one." Today, he says, a strong union is an idea whose time has come.

"Eleven years ago if anyone had said I'd join a labor union I would have been horrified," said another AFT convert and a former FEA representative. "I would not have wanted to associate with blue-collar workers --I don't mean to sound like a snob, but I used to think of myself as a professional. However, the county has long since stopped treating us like professionals."

When Nelson came to Fairfax, he said, county teachers were among the highest paid on the East Coast. Even then, he contends, teacher morale was low -- "not as low as it is now, but you could sense it in the teachers' lounge, a kind of fear."

Nelson contends that the FEA, which has historically represented most teachers, has done little to raise employe morale or bring about other major improvements for teachers.

To support his argument, Nelson brings out charts to show that Fairfax teachers lost economic ground to the cost-of-living even during the era of collective bargaining for public employes -- a time when the FEA was the teachers' official bargaining agent.

Nelson says the purpose of the federation is to reverse the setbacks that teachers have suffered over the past decade.

"Our goal is to win back collective bargaining and then become the (teacher's) bargaining agent," Nelson says.

Right now, the federation has 500 members, up from 250 last January. By comparison, it is estimated that more than 6,000 of the county's 7,200 teachers are FEA members.

Even though the FEA still dwarfs the federation, Nelson believes things can only get better for his tiny union local. He is particularly relentless in his criticism of the FEA, returning again and again to the potential strength teachers would have if they were affiliated with the AFL-CIO.

With the optimism of a union president whose membership has more than doubled during the past 12 months, Nelson says he is out to overwhelm the FEA, which he calls "weak" and a "patsy" for the school administrators.

"(The FEA's) weakness is unquestioned," Nelson says confidently. ". . . Teachers represent only 1.5 percent of the total electorate in Fairfax County. This past election showed that teachers were a handicap to candidates. It was apparent a candidate would win more votes using the teachers as a whipping boy than they would by publicly supporting them."

When the FEA's request for a 20 percent salary increase became public, teachers became a political liability to local candidates, with nearly all -- even candidates with FEA endorsement -- denouncing the association's proposal.

"If the AFT was the majority association, that wouldn't have happened," Nelson says. "The teachers would have had the backing of the entire labor movement. With the AFT, the teachers could promise political candidates they would bring out the vote. The FEA doesn't have any (political) friends."

Claiming that many of this year's 250 new federation members were once in the FEA, Nelson says teachers join the federation when they are fed up with the FEA.

FEA President, Gerry Gripper, however, denies his organization is losing membership. While Gripper says he does not have up-to-the-minute membership tallies, "membership is holding steady, we're right where we were last year at this time."

But officials at the Virginia Education Association, the FEA's parent organization, who cite the FEA as the largest and best organized branch in the state, say December membership in the FEA was 6,300 -- down 250 members since August 1979.

Nelson says when he becomes a full-time union president in February, he will concentrate on "the issues and membership." The primary issue will be collective bargaining.

"We will get collective bargaining back when politicians look back on what we used to have as the good old days," Nelson says. "That's one of the reasons I'm opposed to ending work-to-the-rule. The longer teachers work to the rule, the better the old days of collective bargaining will look."