Tysons Corner is in for a major overhaul, and business leaders in neighboring Arlington County are worried that Fairfax County's gain could be their loss.

Leadership Arlington, a group of local business owners, talked Tuesday of the need for Arlington to stay ahead of the competition once the Dulles Metrorail line, dubbed the Silver Line, connects Tysons to the District and development there kicks into high gear.

Demand for Arlington office and business space is already headed for hard times, business leaders said, with looming federal budget cuts and government agencies unable to afford Arlington's high rent. New buildings in Arlington are now leasing at $50 to $60 per square foot, even though federal agencies were instructed to pay no more than $38, panelists said.

And Arlington is still waiting to feel the full economic hit of the Pentagon's Base Realignment and Closure program, as only 15 percent of the 17,000 defense workers slated to move out of Arlington have done so already.

"Could we see in the next few years Arlington becoming much more of a private-sector community and Tysons being government? I don't know," said Marty Almquist of Avison Young and chairman of the Crystal City Business Improvement District.

But some Arlingtonians remained positive.

"Although I think Arlington is going to be facing competition it's never faced before, we're going to meet that competition, because quite frankly our area is better. You don't build these urban villages overnight," Arlington Economic Development Director Terry Holzheimer said.

Business leaders emphasized that it will take Tysons decades to attract the large numbers of residents and workers Arlington already has.

Local business owner Margaret Mitchell pointed out that Arlington also has the advantage of the Interstate 95 high-occupancy vehicle lanes, which allow "sluggers" and other commuters easy access from Prince William County and points south.

Others said the Silver Line could actually boost Arlington's profile even more as a hub for both the Orange and Silver lines, which will run through East Falls Church in Arlington.

"Location, location, location. Arlington's not going anywhere, and it's because we're in the center," said Brenda Krieger, chairwoman of the Ballston Business Improvement District.

Panelists agreed that Arlington government and developers should keep building and rebuilding roads and offices if it hopes to keep up with Tysons.

"In Arlington, we are ahead of the game," Almquist said, "but our eye does need to stay on that prize."