U.S. Secretary of Transportation Ray LaHood on Wednesday gave local officials 30 days to agree on estimates for what it will cost to finish building the Metrorail line to Washington Dulles International Airport and into Loudoun County. LaHood is trying to broker a deal between the Metropolitan Washington Airports Authority, which is overseeing the project, and state and local officials, who must pay for it and who are claiming that the authority is driving up the rail line’s costs beyond what they can afford.

The transportation secretary met privately with officials from Fairfax and Loudoun counties, the state, and the airports authority and asked them to return in a month with agreed-upon costs that could serve as a basis for further negotiations. Current estimates for the second phase of the project’s construction range from $2.5 billion to nearly $4 billion.