Federal officials said Monday that they want to trade the J. Edgar Hoover Building for a new suburban FBI headquarters rather than pay cash to relocate the agency.

Lawmakers from Fairfax County and Prince George's County -- the early front-runners in the contest to win over the agency -- didn't immediately rule out accepting the Federal Bureau of Investigations' Pennsylvania Avenue headquarters in exchange for the suburban sites they're offering, but they said they need more time to figure out whether the trade would work.

The General Services Administration, the federal government's real estate manager, offered a property swap instead of cash in hopes of reducing the cost of what is expected to be a very expensive move of all area FBI operations into a single suburban headquarters.

The Hoover Building that the GSA is offering to trade is in a prime location in the District, but the building would require extensive renovation that federal officials said could cost $2 billion and take 15 years.

"An exchange of the FBI headquarters not only saves money, but it also promotes efficiency by consolidating staff into a single state-of-the-art facility, shrinking the federal real estate footprint and eliminating multiple leases," said GSA Acting Administrator Dan Tangherlini.

In announcing its interest in a real estate swap, the GSA did recommit itself to keeping the FBI headquarters in the immediate Washington area, which was good news to Virginia and Maryland officials who are putting together competing proposals to win over the FBI and the 12,000 jobs that the headquarters move would bring to the community that wins it.

Fairfax County officials are offering the FBI a warehouse in Springfield that is already owned by the GSA, though officials said they also may consider other offers from private property owners.

"We believe we're very well-positioned to take advantage of this," said Fairfax County Supervisor Jeff McKay, D-Lee. "The best way to save costs is to use assets that you already have."

Prince George's County officials, who still haven't publicly named the sites they intend to offer to the FBI, said the GSA's announcement that it would prefer to do a real estate swap fits in with the county's own plans.

"No other jurisdiction is [courting the agency] in Maryland," said David S. Iannucci, Prince George's coordinator of economic development and public infrastructure. "So we have the unified support of the state ... and I'm absolutely convinced Prince George's County can provide the FBI with the best location."