Sen. Mark Warner weighs in on DC MetroRail expansion to Dulles Airport

Warner, a former governor of Virginia from 2002-2006, pointed out that he supported the project when he led the state he know represents in the Senate.

Warner said that the 15 percent cut in cost he called for did not have to come solely from locating the station above ground, though he made clear that should be an option.

"This 15 percent cost reduction could be achieved, for instance, by switching from an underground to above-ground station at Dulles, reducing the scope of the planned rail yard and exploring alternative financing for the construction of parking garages associated with the rail," he wrote.

Some observers have suggested that the rising costs of the MetroRail expansion to Dulles Airport could become an issue in the 2012 campaign for Virginia's other Senate seat. In that race, former Democratic National Committee Chairman Tim Kaine and former Sen. George Allen (R), who are both  themselves former Virginia governors, are running to replace retiring Sen. Jim Webb (D).