Voters in Northern Virginia's 36th House District are confronted by a clear choice in the Nov. 5 election.

On the one hand, there is incumbent Del. Kenneth R. Plum, 43, a Democrat and public school employe who runs Fairfax County's adult education program. He is backed by the Virginia Education Association, the state teachers' lobby, in his bid for a fourth term. His voting record won a perfect rating from the Virginia NAACP.

Then there is challenger Lloyd L. Thoburn, 24, a conservative Republican who is administrator of his family's for-profit Fairfax Christian School. Thoburn describes Plum as too liberal for the district.

"It's the clearest philosophical choice in the state," said James S. Turpin Jr., executive director of the state party's Joint Republican Caucus.

The Fairfax County district stretches from the semirural area along the Loudoun County line to the high-rises of Tysons Corner, and includes the traditionally Democratic Reston area, which accounts for most of its voters.

Thoburn concedes he has an uphill fight. Each candidate has budgeted about $20,000 on the contest.

Thoburn says his family, including father Robert L., a former GOP delegate himself, and brother John, a one-time state Senate candidate, both of whose campaigns he has run, tried to dissuade him from the race.

But Thoburn said Plum should not be allowed to run again unchallenged.

If he loses, Thoburn said, he will be back in two years: "I won't give him any peace."

Plum describes himself as a leader in the human and handicapped rights area, a moderate on fiscal issues and a native of the Shenandoah Valley "who can talk country talk and get along with the rest of the Virginia General Assembly." He calls Thoburn a "far right-winger," and said: "He probably thinks 90 percent of the people in the world are too liberal."

As it is elsewhere in Fairfax County, transportation is the top issue in the district.

Both men said they would fight for more Northern Virginia highway money from the General Assembly, support the proposed Springfield Bypass, and endorse study of a light rail transport to Dulles Airport.

The candidates differ on Metro: Plum pledges to work with the Northern Virginia delegation to preserve the $21 million subsidy, and Thoburn questions whether money for Metrorail would be better spent on roads or bus service. Thoburn said one way to build new roads is to charge tolls for highways such as the Springfield Bypass; Plum said the one toll road in Northern Virginia is enough.

On the other big issue -- education -- both men support elected school boards as a local option. But on the question of state funding, the men's differences echo those of the gubernatorial candidates of their parties. Plum favors full funding by the state government of its "standards of quality," the program and staffing guidelines local districts must meet. It can be done without a tax increase and the additional state funding would save Fairfax County $22 million a year, he said.

Thoburn does not support full funding, saying some of the standards -- a large across-the-board teacher salary increase, for example -- are questionable. "We need quality schools," Thoburn said. "But Plum's attitude is to throw money at the problem."

Unlike some Christian educators, Thoburn said he sees no place for prayer in public schools, and does not plan to work for tax credits for parents who send their children to private or parochial schools.

Then there are Thoburn's charges about Plum's record, most of which Plum calls "half-truths":

*Thoburn said Plum voted against a bill to confiscate illegally seized property of drug dealers. Plum said he was a sponsor of the final bill, and voted only against an intermediate version of doubtful constitutionality.

*Thoburn supports capital punishment and points to Plum's vote against the death penalty for child murder. Plum opposes capital punishment, saying it will not bring back the dead victims or prevent future crimes.

*Thoburn said Plum wants taxpayers to "be required to fund abortion." Plum said he supported a bill to allow state-paid abortions for cases of rape, incest or severe fetal deformity; only seven took place in the first 18 months after the bill took effect, he said.

*Thoburn said Plum voted to fine people $25 if they do not wear seat belts, and said that is none of the government's business. Plum said government has a right to require seat belts because some people who do not wear seatbelts are severely injured in accidents and taxpayers pay the costly medical bills.

Then there are Plum's accusations about Thoburn:

*Plum said Thoburn has raised the right-wing issue of secular humanism in the schools. Thoburn said it is not a campaign issue for him.

*Plum suggests that Thoburn, whose family lost a local attempt to build an expanded school and a housing development on land it owns in Oakton, would try to use his legislative power to win change. Thoburn denies this.