Now the U.S. Senate has joined the fight to keep the Montgomery County planning board in Silver Spring.

In a letter to County Executive Charles W. Gilchrist, Sen. Jennings Randolph (D-W.Va.) has cautioned that relocating the board could make it more difficult for the county to persuade the federal government to build a new Nuclear Regulatory Commission (NRC) headquarters in the declining urban area.

Randolph chairs the Committee on Environment and Public Works, a powerful panel that has jurisdiction over the NRC as well as over construction of federal buildings.

Gilchrist and the County Council so far have resisted pleas from Silver Spring business and community leaders and the planners themselves to reconsider the scheduled move of the Montgomery arm of the Maryland-National Capital Park and Planning Commission to the county office complex under construction in Rockville.

Sources say the senator's letter could help change their minds.

Gilchrist appeared distressed when asked about the letter, and said he wanted to discuss it with his staff before giving an opinion.

"It's a very serious letter and I will have to respond," said the executive in an interview. "It is very important for us to remain in the running for the NRC."

In his Dec. 19 letter, Randolph chided the county for planning to move one of its own major agencies out of Silver Spring while it begs the federal government to help revitalize the city by locating the NRC there.

Calling the action inconsistent, Randolph wrote, "I would appreciate it if you would explain this proposed move and why, in light of it, our committee should continue to ask that Silver Spring be considered equally with the District of Columbia, where there is a strong tangible commitment by the city government to the redevelopment areas being considered for NRC."

The District is Montgomery's chief competitor for the proposed NRC headquarters. White House policy dictates building new government facilities in economically depressed areas.

Once a thriving commercial center, Silver Spring gradually slipped into hard times as affluent suburbs and accompanying shopping malls were built farther from Washington.

The county hopes to reverse the trend with a $3.5 million urban-renewal program that will include new street lights, sidewalks and other improvements geared to attract new businesses.

The proposed NRC headquarters would consolidate the regulatory agency now scattered in five offices, four in Montgomery County and one in the district. It will bring 2,800 lunch-buying, shopping employes to the location it ultimately chooses.

Randolph's letter arrived just as Silver Spring business and community leaders had refueled the fight to keep Montgomery County's planners and their 150 staff members in their present Georgia Avenue headquarters.

Earlier this year, the County Council, at the request of Silver Spring business and civic leaders, twice reconsidered the move but voted both times in favor of it.

But because of continued pressure from adamant Silver Spring residents, the council recently held public forums on the issue and will vote on it again in early January.

Councilmember Neal Potter maintains the county wants the planning board in the same building with other county agencies for the same reason the NRC wants to consolidate its offices: efficiency and improved service to the public.

"We now have to consider whether the difference it (the move) would make to Silver Spring would outweigh increased county government efficiency," Potter said.