The airports authority in charge of building the Metrorail line to Washington Dulles International Airport must drop its preference for union labor if the Silver Line is to become a reality, federal, state and local officials agreed Wednesday.

Officials turned up the pressure on the Metropolitan Washington Airports Authority to back down from its insistence that union labor be used at a meeting U.S. Transportation Secretary Ray LaHood organized with officials from MWAA, Virginia, Metro, and Fairfax and Loudoun counties.

The future of the $6 billion Rail project's second phase has been in doubt in recent weeks as officials squabbled over the project's costs and with the airports authority over its preference for union labor that officials said would only increase those costs in violation of Virginia's right-to-work law.

LaHood said after the private half-hour meeting that all sides agreed the labor issue was "the only sticking point" and that officials would meet again to work out a solution.

"This project will move forward. The people of this region will have the opportunity to get on a train and take it all the way to Dulles Airport and stop in communities all along the way and even go beyond to Loudoun County if they like," LaHood said. "I believe we'll be able to work [the labor issue] out."

Loudoun County Board of Supervisors Chairman Scott York said that while no promises were made, he was hopeful that MWAA leaders would be able to convince the authority to drop its labor preference.

"They just were not as defensive about it as they have been in previous meetings, as well as with me in private," York said. "So I'll just say what was said and the body language -- it seemed to me they understand this has got to go away."

If they don't, York has warned previously, the all-Republican Loudoun board could withdraw from the Rail project, forcing other partners to reorganize all of their financing agreements.

Virginia officials, meanwhile, are weighing the possibility of seizing control of the project away from an airports authority the state claims ignores its concerns, Virginia Secretary of Transportation Sean Connaughton said.

"The Commonwealth is interested in moving this project forward," he said. "And we will do whatever is necessary to ensure that happens."