In a pork-barrel battle that pits Northern Virginia against the Maryland suburbs, Sen. Barbara A. Mikulski (D-Md.) has tried to stop the prestigious National Science Foundation from moving out of the District to a new home in Arlington.

Mikulski, a ranking member of the Senate Appropriations Committee who oversees the foundation's budget, has used her position in an attempt to bring the agency to Maryland.

The fight over the Science Foundation (NSF), which would bring visibility and economic benefits to its new location, reflects another facet of the relationship between the Maryland and Virginia congressional delegations. While often united by their concerns for the huge number of federal employees in their constituencies, they are also competitive over the spoils of the bureaucracy.

The battle for the foundation has sparked particularly intense behind-the-scenes maneuvering by Mikulski and Virginia Sens. Charles S. Robb (D) and John W. Warner (R).

"Part of our job is to represent Maryland and our constituents," said Mike Morrill, a spokesman for Mikulski. He said Mikulski has been careful "not to step in and force the process," but added, "We are unhappy with the way Maryland's bids were treated and we want Maryland treated fairly."

Steve Johnson, a spokesman for Robb, called the dispute "heavy-duty politics. People act in the way they think will benefit their people and their constituency. And in Washington, all's fair in love and war."

The feud simmered for months until September, when Mikulski tried to derail the foundation's moving plans.

Arlington's Ballston area was tentatively selected as the foundation's new home this spring, following an 18-month competitive bidding process that included sites in Maryland, Virginia and the District. Mikulski and Maryland Gov. William Donald Schaefer immediately objected.

Several months later, when the Senate Appropriations Committee was considering the agency's 1991 budget, Mikulski inserted language forbidding the foundation to move.

The stay-put clause sparked adamant protests from Robb and Warner, who persuaded Mikulski to remove it just before the bill became law. But last month the foundation's moving plans were suspended by its acting director, Frederick M. Bernthal, who cited budget constraints.

The Science Foundation is now caught in an interstate shoving match, with Mikulski and Schaefer contending that the site selection process was stacked against Maryland, and Virginia legislators calling Maryland a sore loser. Warner, a Republican, recently intensified the fight by appealing to the White House, hoping GOP officials there will side with him over Democrat Mikulski.

"We hope the White House will look at this case and decide it on the merits," said Glenn Davidson, Washington liaison for Virginia Gov. L. Douglas Wilder. "We believe Virginia is the winner fair and square."

This is not the first time Virginia and Maryland have fought over a federal agency, but lawmakers say it is among the most notable battles.

In recent years, as major bureaucracies have moved out of the District, seeking lower rents and newer facilities in the suburbs, battles have erupted over agencies such as the Navy and the Internal Revenue Service. Virginia got the Navy; Maryland, the IRS.

But the Science Foundation is particularly sought after. Legislators in both states compare it to the National Institutes of Health, the Bethesda-based research organization that has helped spur high-technology growth in Montgomery County. Lawmakers hope the science agency would create similar ripples.

The foundation currently occupies parts of two buildings in downtown Washington. According to Geoff Fenstermacher, a foundation administrator, the agency decided to move in 1988, primarily because its quarters cannot easily be outfitted with advanced computers and equipment.

According to officials at the General Services Administration, the federal government's property manager, more than 50 potential landlords expressed interest in renting to the foundation. Among them was the University of Maryland, which wanted the agency to move to its College Park campus. But the foundation had adopted criteria requiring that its new home be within 2,000 feet of a Metro station, which effectively ruled out any campus site.

When GSA officials identified two buildings in Ballston as the finalists for the lease, Schaefer and Mikulski reacted. "Maryland believes the university would be ideal for the foundation," said Monica Healey, Shaefer's Washington liaison. "We were concerned about the Metro requirement, and we raised questions about the integrity of the selection process."

John Myers, a GSA leasing official, described the bidding process as "not unique or unusual. It's something we normally do. We felt it was fair."

While Mikulski's attempt to block the move was eventually withdrawn, the House and Senate Appropriations committees did cut $5.5 million in moving expenses from the foundation's 1991 budget. Bernthal, the foundation's acting director, cited that cut when he suspended moving plans last month.

As chairman of the Senate Appropriations subcommittee that oversees the foundation, Mikulski has considerable influence over the agency's budget. But Morrill, Mikulski's spokesman, said that she has not attempted to punish the foundation for contemplating a Virginia location.

"Because we chair a subcommittee, it can get real dicey whether what we are doing is fair," Morrill said. "But we were not going to use her position to benefit Maryland. We have not been in communication with" foundation officials. Ray Bye, the foundation's chief lobbyist, said "there's not any kind of intimidation" from Mikulski regarding the move.

But Susan Magill, Warner's administrative assistant, said, "I don't know of another {agency move} that has gone so far in the process and gotten off the track. The process was basically finished.

"My impression is the {foundation} went out of its way to be fair to Maryland. Now it's come down to hardball politics."