Virginia may be a red state and some Northern Virginia communities may be blue, but in the 37th House District, a suburban mix of Democrats and Republicans just outside the Capital Beltway, the political colors blend into purple.

For years, this area of central Fairfax County and Fairfax City supported GOP candidates in presidential and state elections.

But last November, it went Democratic in the presidential race. In 2001, Democrat J. Chapman Petersen barely upset Republican John H. "Jack" Rust Jr., who had held the House of Delegates seat for a decade. Petersen handily beat Rust in a rematch two years later.

Could the seat be going Democratic? Leaders in both parties say they don't know. But with Petersen bowing out to run for lieutenant governor, the 37th has become one of the state's few wide-open districts and a key test of the GOP's grip on central Fairfax.

"We are paying special attention to it," said House Speaker William J. Howell (R-Stafford). "I'd love to take it. It's not a slam-dunk Republican seat or a slam-dunk Democratic seat."

Said Dan Drummond, the Fairfax City Democratic chairman: "It's obviously a top target for both Republicans and Democrats. There's no question it's in play."

Two Democrats and two Republicans are running in the June 14 primaries.

On the GOP side is newcomer James L. Kaplan, 34, who was the first to declare his candidacy, in January, and former Fairfax City mayor John Mason, 70, who threw his name in just before the filing deadline in April.

The Democratic primary involves at-large Fairfax County School Board member Janet S. Oleszek, 58, who was the top vote-getter in the 2003 school elections, and David Bulova, 36, a member of the Soil and Water Conservation Board and the son of Fairfax Supervisor Sharon S. Bulova (D-Braddock).

The candidates focus on the same issues: transportation, taxes, education. But they vary widely in their experience and background.

Kaplan, who works in marketing and lobbying for a financial services firm, said a Republican delegate would be more effective because the party holds a majority in the General Assembly. He said he would work to get more money back from Richmond for schools and roads. He was also critical of Mason for raising taxes while he was mayor.

"John voted to increase property taxes. . . . He was a proponent of the sales tax referendum, which failed in Fairfax," Kaplan said. "As a homeowner, I have grave concerns about how taxes are increased."

Mason called Kaplan "a nice young man" who "lacks real experience in government." Mason said taxes went up everywhere in Northern Virginia because housing assessments soared. But he said that while he was mayor of the city, he cut the tax rate to a level lower than in any other jurisdiction in the region.

He added that no one in the race can match his government experience, which includes 12 years as mayor. "The question for the voter is who has the proven track record and the experience to work well in Richmond for the benefit of this district," Mason said.

Kaplan criticized Mason for making political contributions to Democrats such as Sharon Bulova and Lt. Gov. Timothy M. Kaine, who is running against Republican Jerry W. Kilgore for governor.

Mason, noting that elections are nonpartisan in Fairfax City, countered that "the notion of crossing party lines to establish good alliances is a reasonable and prudent thing to do."

On the Democratic side, David Bulova touted his community involvement as chairman of the Fairfax County Consumer Protection Commission and as an environmental planner with the Northern Virginia Regional Commission, where he worked on Chesapeake Bay issues. He was elected countywide in 2003 to the Soil and Water Conservation Board and also has been involved in gang prevention and public safety organizations.

"I've dealt with consumer protection, environmental issues, crime protection, gang violence," Bulova said. "It's that combination of public service that puts me in the strongest position to go down there and hit the ground running."

Oleszek touted her background in education. Over the past two decades, she has been a substitute teacher in special education, a lobbyist for the Virginia Parent Teacher Association and most recently a board member of the largest school district in Virginia. But she said she has "a lot of interests that school board doesn't fulfill, although education is my most important issue."

"I'm concerned about the status of women and children's health care issues apart from education," she said. "I'm very concerned about seniors, my neighbors, who are struggling with their medication and their reimbursements."

In addition, Oleszek said, she could more effectively stand up for women's civil liberties and reproductive rights. With the number of women in the House of Delegates down to 13 -- and two of those retiring -- Virginia needs more women in the General Assembly, she said.

She was not concerned about Bulova's name recognition. "It's a highly regarded name, no question; we all are very fond of Sharon, who has done a great job," Oleszek said. "But I'm not running against Sharon; I'm running against David."

Although his mother has had a huge influence on his budding political career, Bulova said, "I've tried very hard to make sure that I can stand on my own two feet and more, and that I'm a viable, strong candidate in my own right."