Who persuaded a powerful U.S. senator from West Virginia to rush to the defense of Silver Spring in a battle over a Montgomery County agency?

No one seems to know but after receiving some heat from Sen. Jennings Randolph (D-W.Va.), the County Council last week reversed a longstanding decision to move the county planning board from economically ailing Silver Spring to new headquarters in Rockville, the county seat. The vote was 4-0 with three abstentions.

County Executive Charles W. Gilchrist and council president Scott M. Fosler visited Randolph the day before the council vote. Their trip to the senator's office was the result of a harsh letter Randolph sent Gilchrist last month, criticizing the proposed move.

Randolph chairs the Senate Public Works Committee, the group considering whether to locate new Nuclear Regulatory Commission (NRC) headquarters in Silver Spring or in the District of Columbia.

In his letter to Gilchrist, Randolph said it was "highly inconsistent" of the county to move a major agency out of Silver Spring while it urged his committee to move in the NRC.

The NRC, which has an estimated $50 million annual payroll, is now spread out in several offices in the District and Montgomery County. The move would bring together 3,000 employes in one headquarters.

Officials in both Montgomery County and the District claim the move could help depressed neighborhoods with an influx of lunchtime consumers.

A moratorium on new federal buildings, declared by Randolph's committee last spring, apparently has not dashed the hopes of either jurisdiction for eventually getting the NRC headquarters.

Council president Fosler, commenting on last week's vote, said, "All things considered, our priority is doing what's best for Silver Spring and in this particular instance NRC was a consideration."

Opponents of the move, including Silver Spring business and community leaders and planning board officials themselves, are rejoicing.

"I'm delighted we can now put our full efforts into getting the NRC in Silver Spring," said council member Esther Gelman. A former planning board member, Gelman was one of the leaders in the fight against the move.

But who persuaded Randolph to write the letter?

No one seems to know for sure. So far, each of the following suspects denies he or she was the person who urged Randolph to fire what proved the final round in the long-running local dispute:

Sen. Paul S. Sarbanes (D-Md.), Sen. Charles McC. Mathias (R-Md.), Rep. Michael Barnes (D-Mont.), State Sen. Victor Crawford (D-20), County Council member Esther Gelman, County Council member Mike Gudis, planning board chairman Royce Hanson, Silver Spring Chamber of Commerce president E. Brooke Lee III, John Dulaney, who is an attorney for Linowes and Blocher, a major zoning law firm headquartered in Silver Spring, Gus Gentile, who is Silver Spring Democratic leader, John Yago, a county resident who is staff director of Randolph's committee, and D.C. Mayor Marion Barry.

Randolph said, through an aide, that he received a letter from a Montgomery County individual who did not want his name revealed.

"The letter stands on its own. It's not a favor. It's not that sort of thing at all," said one Randolph staff member. "They just told us one thing and they're doing another, and someone told us about it."

Montgomery County officials who frequently find their plans plagued by wealthy and well-connected citizens, say they are upset but not surprised by the federal intervention.

"Here in Montgomery County we have so many people who work on the Hill that we get used to it. We don't even speculate," said Tom Stone, one of Gilchrist's assistants.

"It could easily have been any of 300 people," mused another county official. "In Montgomery County senate staff are in everyone's carpool or in the PTA. We're always faced with this kind of clout."