It was time for closing arguments at the Loudoun County League of Women Voters debate in Sterling between Del. Richard H. Black (R-Loudoun) and Democratic lawyer and lobbyist David E. Poisson.

"David Poison," the conservative delegate said, mispronouncing his opponent's last name, "applauded the biggest tax increase in Virginia history knowing that two-thirds of the money would go south never to return. . . . Poison is a tax-and-spend liberal."

From the crowd, supporters of Black's opponent shouted "It's pwah-SAHN!"

Despite their protests, Democrats are hoping their candidate really does spell poison for one of Virginia's best-known legislators in Tuesday's election.

Black, a four-term delegate, is a well-known leader in conservative circles, perhaps best known statewide for sending tiny plastic models of fetuses to fellow lawmakers before votes on abortion restrictions, which he favors. This year, he urged supporters to protest before the Loudoun County School Board after a student-written play dealing with homosexuality was performed at a high school.

The House district, which extends through parts of Sterling and Ashburn, has been one of the state's most reliably Republican regions, an area where President Bush beat Sen. John F. Kerry (D) handily in 2004 and where, unlike much of the rest of the state, Republican Mark L. Earley ran ahead of Mark R. Warner in the gubernatorial contest four years ago.

This fall, Bush's popularity has sagged and Democratic gubernatorial candidate Timothy M. Kaine is in a close contest with Republican Jerry W. Kilgore. Meanwhile, Black is facing a politically savvy opponent who has spent years as a lobbyist for businesses and trade organizations.

But this race has been particularly hard to handicap because the district includes vast tracts of developments built after the delegate's race in 2003. The number of registered voters has ballooned 13 percent in the past two years. Both campaigns have been well funded, but Poisson has taken in close to $30,000 in the past week, a sign that Democratic groups believe Black is vulnerable.

"This is a district that has had a huge influx of new voters," said Sen. William C. Mims (R-Loudoun), who said persuading newcomers to turn out would be a key to victory for either side. "I don't believe this electorate is dominated by partisans. I believe it's dominated by independents. We're in some new territory right now."

That is the population Poisson has been courting. He says Black has spent too little time addressing traffic congestion and getting more state money for schools.

"I'm talking about a vision for the future of our children, better education, more opportunities for higher education and a better transportation system," Poisson said.

Black counters that he has worked hard to improve Route 28, an often-blocked commuter route. He says Loudoun schools are doing well, and it makes little sense to push for higher state taxes given that tax money collected from local residents is returned to their school system.

Black has pledged to oppose all tax increases. The county's growth will only help him, he said, because his views are a better match for newcomers.

"My opponent has been endorsed by the Virginia Partisans Gay and Lesbian club, and I have been endorsed by the Virginia Society for Human Life," he said.

Poisson said he supports abortion rights and legal benefits for same-sex couples. But he said he opposes same-sex marriage and did not seek the endorsement of the partisans organization. He said voters are far more interested in talking about growth, schools and roads.

"I think the fact that he doesn't have a record worthy of any mention forces him to try to use things like that to try to divide people," Poisson said.

On education and transportation, which voters have repeatedly ranked among their most important issues, some of Black's Republican colleagues in the county have given him only temperate support.

Loudoun School Board Chairman John A. Andrews II (Potomac), a member of the local Republican committee, said he is supporting all of the party's candidates. But when asked if Black has been an effective advocate for county schools, he declined to comment. "I know how that looks," he said.

Poisson has spent months campaigning to moderates and newcomers, in an attempt to overcome a strong Republican effort to get out the vote has rolled over Black's previous opponents. The Democrat's supporters include the Women for Poisson, who have promised to use long lists of friends from PTAs, book clubs and bunco game groups to convince other mothers that Poisson would do more for their children's schools.

Debbie Hawk, a 14-year district resident organizing the effort, said Black is a polarizing figure who has turned voters off with his no-holds- barred campaigning techniques.

There is the repeated mispronunciation of Poisson's name -- "sophomoric" says the Democrat, while Black says he remains unsure how to say it. Black has also tried link Poisson to Sen. Richard J. Durbin (D-Ill.), who this summer apologized for comparing the treatment of U.S. detainees to the behavior of the Nazis. Poisson last worked for Durbin 16 years ago.

Poisson supporters have also cried foul over a candidate questionnaire published in the Loudoun Connection, a local newspaper, where Black, a decorated Vietnam War veteran, wrote that Poisson "avoided the draft."

In fact, Poisson had a high draft number, and later a student deferment; he was never called. Black defended his criticism, saying that history warrants his claim.

Michael P. Farris, president of Patrick Henry College, a Christian institution based in Loudoun, said Black is a formidable opponent with a passionate core of supporters. But, he said of the race, "I'd pay attention."