Loudoun County officials are scrambling to find a new site for a commuter parking lot in Leesburg before time runs out.

Since last fall, the county has leased the parking lot at the former Kmart on East Market Street, but officials say they will have to leave that lot because the site is slated for development into a retail strip with smaller shops. Although the county has not received the official 60-day notice to vacate, it is expected any day.

"To get everybody to agree on a location is an involved process," said John J. Clark, Loudoun County transportation director. Clark has been seeking and evaluating potential sites with the input of Leesburg officials, residents and county staff.

About 300 vehicles park at the Kmart lot on weekdays. Passengers then take a park-and-ride bus into Arlington or the District. The popular service also has lots in Purcellville, Hamilton and the Sterling/Ashburn area, but the Leesburg location is used mostly by town residents.

A number of town officials -- including Mayor Kristen C. Umstattd and Town Manager Robert S. Noe Jr. -- favor a commuter lot on Tolbert Lane at the Greenway, just north of Leesburg Executive Airport in the planned Oaklawn at Stratford development.

Umstattd and Noe have met with county Supervisors Jim E. Clem (R-Leesburg) and Sally R. Kurtz (D-Catoctin), who represent the areas that are home to many Leesburg commuters, to get their support for the Oaklawn site.

Oaklawn's developer wants to build an office, retail and residential complex. That means the portion of the development available for parking would require building a garage to attain the minimum of 500 spaces to accommodate the county's projected need.

"The service is very popular, and it has been expanding," Clark said.

He estimated it would cost more than $10 million to acquire the Oaklawn land and build a garage. "It's more than we would be able to afford," he said.

The county has designated $5 million for the lot.

The county is considering another site at the location for the Philip A. Bolen Memorial Park south of Leesburg. The land, owned by the county, would be accessible from Sycolin Road outside Leesburg's southern town limits. One possibility, officials said, would be to build a smaller lot at Oaklawn and combine it with a lot at the Bolen park.

"Together they would provide about 600 spaces that would give us what we're looking for," Clark said.

Clark said that the new sites would not be ready for about 18 months and that the county was looking at locations for an interim lot.

Leesburg Town Council member Robert J. "Bob" Zoldos has urged consideration of a site near Potomac Station, at the southeast corner of Battlefield Parkway and Fort Evans Road, northwest of the new Giant supermarket. "This site is already clear and ready for construction," he said.

But other council members have countered that the site would cause congestion by bringing traffic from western Leesburg through town.

Clark said the Potomac Station site, with about a 300-vehicle capacity, could be used as an interim site for one or two years.

Umstattd said it was important that the county specify in writing how long it would use a temporary site. Other officials, such as Clem, oppose using a temporary site at all, saying it would be a waste of money to improve a lot that would be used only in the short term.

"We need to go ahead and find a permanent site," Clem said, adding that he hoped the owners of the Kmart lot would grant a brief extension.

Clem suggested that the county could negotiate a deal with the Oaklawn developers to make that site more affordable.

In the meantime, Umstattd said commuters may need to use extra spaces at Heritage High School until the situation was resolved. Clark, however, said the availability of parking at the school was not certain.

"We're looking for ways to get cars off the road," Umstattd said. "We have a fair number of constituents who take the commuter bus to their jobs, and they are desperate to keep the commuter bus a viable option in Leesburg."