Leesburg is a small town where you can still find a parking place on the main street and a cat can sun itself undisturbed in a shop doorway.

But a wave of development is coming from the east with such speed that it threatens, in the view of many residents, to engulf the town.

Development and what Leesburg and Loudoun County will look like as it moves through the county is an underlying issue in this November's Board of Supervisors election.

The Leesburg magisterial district, one of eight in the county, makes up the northern two-thirds of the town. It is represented by Democrat Charles A. Bos (pronounced boss). With a population of nearly 8,000, the district has about 3,800 registered voters.

Bos, 47, a veteran Leesburg politician who served seven years on the Leesburg Town Council, was appointed in December to finish the unexpired term of supervisor Frank Raflo, a Democrat who retired because of poor health.

His challenger, Republican Georgia W. Bange (rhymes with range), 57, is a newcomer to elective politics.

As in so many races in Virginia's outer suburbs, there is little disagreement between the two candidates over what the issues are -- managing traffic and controlling development -- or on how the candidates would deal with them.

Both want to see the Dulles Toll Road entended to Leesburg, a measure most observers agree would reduce congestion on Routes 7 and 28. Both want to promote cooperation between Leesburg and the county and both want to find ways to control development and growth in the county, but both point out that beyond a certain point, local governments cannot limit landowners or developers.

The only issue on which they appear divided is the $15 million bond referendum set for Nov. 3 for the purchase and development of a 357-acre parcel of land south of Rte. 7 known as the Claude Moore tract.

Bange does not believe the county should buy the land. "I'm in favor of open space, but I would not like to see public funds used for it," she said.

Bange's position is that the county should wait and see whether Moore prevails in his suit against the National Wildlife Federation, which accepted Moore's donation of his land 12 years ago, then sold it to a developer.

If Moore is successful, says Bange, there is the possibility that he might be persuaded to donate the land to the county.

"In the best of all possible worlds," Bos counters, "Moore would prevail and then donate his land to the county. But we can't depend on that."

Passing the bond would give the county flexibility, he said. "We would be under no obligation to spend the money if the land were later donated to us."

Bos added that he supports the bond with the stipulation that purchase of the Moore tract not take priority over purchase of parks and recreation facilities contained in the county's comprehensive 10-year plan.

In the absence of major differences with his opponent, Bos says he is hoping his "experience and capability" will persuade voters to return him to the board. Although he has the advantage of incumbency, he won his 1984 election to the town council by 63 votes.

"The key to solving many of our problems, like transportation, is interjurisdictional cooperation. It's difficult for a new person to develop the contacts to do that quickly," he said.

A 15-year resident of Leesburg, Bange, who works as a licensed counselor at the Colonial Funeral Home in Leesburg, says she is "a people person," with a "common-sense approach to issues." She has just completed a one-year term as state president of the Business and Professional Women's Club.

The mainstay of her political position is fiscal conservatism, she said, and if elected, she said she would be loath to tap taxpayers' pocketbooks for public programs, such as parks.

"I would like to see the private sector and the public sector work more together," she said.

Bos has lived in Leesburg since 1970 and is the owner and operator of a foreign car retail and service company there. Bos, who lives in a circa 1830 house, said he has completed only three years of work on a 20-year plan to renovate the house.

Preservation drew him first into Leesburg affairs as a member of the Board of Architectural Review, which rules on the compatibility of new construction with the town's historic district.

Bos and Bange both say they are keeping the campaign on the "up and up," campaigning the old-fashioned way by meeting people face to face and attending candidate nights in the county. "It's a low-key, friendly campaign," Bange said. "We're both very interested in our community."