Kathleen K. Seefeldt won her seat on the Prince William Board of County Supervisors 12 years ago after a two-way primary fight and a general election campaign against two independents.

Since then, no one has opposed her -- until now. Enter Republican Gregory L. Cebula, a newcomer to elective politics.

Seefeldt, a Democrat, has represented the Occoquan District on the seven-member board since January 1976, serving as its chairman for six years. As the board's senior member, Seefeldt could be expected to have instant name recognition in her district, which, with 32,270 residents, ranks second in the county in population, behind Coles. However, many of her constituents are recent arrivals to the district, nestled along the banks of the Occoquan River, opposite southern Fairfax County.

Seefeldt's success at the polls Nov. 3 will depend to some degree on how well she does among those new arrivals, including more than 3,000 voters who moved into the district since the last board election four years ago. There are more than 10,000 registered voters in the district.

Seefeldt, a 52-year-old former English teacher, said she hopes her experience and record will persuade the voters in her fast-growing district to return her to office for a fourth term.

Seefeldt, who is known for her businesslike managerial style, speaks proudly of her record and stresses her involvement in transportation issues -- at the top of nearly every county resident's list of local problems, including Cebula's.

An employe of Diversified Data Corp. in Springfield, Cebula claims to be the only "commuter" running for the board. "I'm not a politician," he says. "I'm a concerned citizen."

Cebula is clearly gearing his campaign to commuters and their concerns. As a regular driver to Springfield, he says, "I know the frustrations" of commuting.

While this approach is likely to fall on receptive ears, it also may fall short of landing Cebula a seat on the board. Seefeldt appears to have solid support in the district, and Cebula remains an unknown to most residents, according to observers.

"He simply hasn't punched any tickets where politics is concerned," said Suzie Takacs, a Lake Ridge resident who said she is a Republican but plans to support Seefeldt.

The Occoquan District more closely resembles its northern neighbor, Fairfax County, than it does any other magisterial district in Prince William. It stretches from the planned community of Lake Ridge, with its well-tended lawns and trim town houses, to the old established town of Occoquan, where another antique or craft shop seems to open every week, to the outlying areas of Woodbridge between Rte. 1 and I-95.

In stressing transportation issues, Seefeldt has moved beyond the boundaries of the district. Last year Gov. Gerald L. Baliles appointed her to the Commission on Transportation in the 21st Century, on which she heads a subcommittee on local government.

"We need more flexibility locally where transportation is concerned," she said in a recent interview. "We are very restricted."

Seefeldt also noted that the county managed, from 1980 to 1985, to exact $15 million in road money from developers in return for favorable zoning actions. "We received only $5 million from the state during that time," she said.

Seefeldt takes some of the credit for exacting such concessions from developers. Riding herd on them has been one of her primary roles on the board, she said.

Last year Seefeldt was honored by the American Planning Association for "her outstanding contributions to local planning." While she was chairman of the board, she led a successful effort to update the county's land-use plan, zoning ordinance and subdivision regulations.

Seefeldt claims a record of helping to control growth in the county, although she is quick to point out that controls are limited because most of the development being built now at a furious rate was granted zoning in the 1960s.

She said she had insisted on incorporating input from local civic associations into the planning process, and added that Prince William County was beginning to attract the commercial growth it needs to strengthen its tax base (the commercial share of the county's tax base rose from 8 percent to about 14 percent in the last two years).

Cebula said he, too, is concerned about development, but that traffic is his main concern.

He said he would like to see more regional cooperation in solving traffic problems, and that he wants traffic lights synchronized during rush hour. In addition, he said the high-occupancy-vehicle lanes on I-95 should be extended to the Stafford County line. The state highway department has long-range plans for such a project.

Unlike Seefeldt and the majority of voters in her district, Cebula did not support last November's unsuccessful county bond referendum. Of the $42 million that the voters rejected, $30 million was to have gone for road construction.

"I do not think the county should get into the roads business," Cebula said.

He also has proposed that the county do away with its personal property tax on automobiles because, he said, cars are essential to people's livelihoods.

Like Seefeldt, Cebula lives in the Lake Ridge area and has been active in the community's civic association. He said he has concerns about the impact on his neighborhood of the Lorton prison and landfill, just across the Occoquan River.

"What we need to do is make the voice of Occoquan heard in Fairfax County," he said.

Seefeldt and Cebula reported raising more than $4,000 each as of the Labor Day weekend.