The jury is still out on a location for a future rail stop at Dulles International Airport after project officials said they needed more time to compare proposed sites and consult with partner localities concerned about the station’s cost.

A committee of the airport authority’s board of directors deferred a preliminary vote Wednesday on a location for the station, the same day it postponed a vote on a controversial new executive after the abrupt resignation of a board member.

But it did decide to drop one site option, an underground stop leading into the main terminal, citing its high cost estimates.

“We recognize the cost is prohibitive,” board member Mame Reiley said.

That leaves an above-ground site adjacent to the north garage or an underground location beneath the hourly parking lot. The underground location would be closer to the terminal but more expensive and would not be completed until early 2017 compared with late 2016, officials said.

In choosing a site for the station, “we have to remember the traveler’s convenience,” said Reiley.

The committee agreed to hold a special session on April 6, the same day the full board meets, during which it will recommend a location for the rail stop. The entire board is then expected to cast a final vote.

The underground option would cost either $912 million or $949 million to build depending on the construction method, according to a report released Wednesday by the airport authority. The above ground station would cost $587 million to construct.

Airport authority officials cited about a $350 million difference between both options. However, the project’s consultants estimated a $240 million difference.

Committee members decided to delay their vote to further examine the discrepancy between the airport authority’s cost estimates and the consultant’s estimates.

“What I keep hearing from our partners is that they want the cheapest mode,” said former congressman and board member Thomas M. Davis III.

In a February letter to airport authority chairman Charles D. Snelling, Sharon Bulova, chairman of the Fairfax County Board of Supervisors, said that Fairfax would be unwilling to fund a station more expensive than the above ground option.

“If the Airports Authority Board favors an alignment that is more costly than the aerial alignment, then the Airports Authority should fund the differential without impacting Fairfax County or tolls on the Dulles Toll Road,” Bulova wrote.

In January the airport authority dropped a proposed outdoor site for the airport station, citing the cost and scope of the project and its potential to ruin views of the terminal, an architecturally significant building designed by Finnish American architect Eero Saarinen.

The Metropolitan Washington Airports Authority is building the Metro rail extension to the airport and to Loudoun County.