The political action arm of the influential Metropolitan Washington Board of Trade has decided not to endorse any candidate for D.C. mayor, saying that the business community believes the three front-running Democratic candidates are all "strong and well-qualified."

At the same time, the board's political action committee said it would spend about $10,000 more ($5,000) apiece promoting the candidacies of two Democrats it already money to: D.C. Councilman Arrington Dixon for the council chairmanship and real estate executive H.R. Crawford for an at-large council seat.

R. Robert Linowes, a zoning attorney and president of the board, has said repeatedly this year that it is "proper, necessary and appropriate" for the business community to be involved in politics, a position he said was not inconsistent with the board's nonendorsement of mayor.

Referring to the principal Democratic mayoral contenders - Mayor Walter E. Washington City Council Chairman Sterling Tucker and councilman Marion Barry - Linowes said the city would be "well-served if any one of the three is elected."

Marsh S. Marshall, president of the M.S. Ginn & Co. office supply firm and head of the board's political action group, said all three were candidates who "understand the business community and the needs of the business community.

"None of the three could hurt the business community," he said.

He said that Washington, Tucker and Barry all have support in the District of Columbia business community. However, Tucker has received substantially more designated contributions channeled through the board's political action arm, $20,625 to $7,875 for Washington and $5,550 for Barry. Other contributions from business ex-executives have been sent directly to the three campaigns.

The Board of Trade, for decades the city's dominant business group, had niver endorsed political condidates until recently when it said its support of Dixon and Crawford and sent them $1,500 and $1,000, respectively, the maximum allowed in their individual races.

Marshall said the board's political action committee has about $11,500 remaining in a fund composed of donations from board members that were not designated for any specific candidate. He said about $10,000 of this would be used to produce and buy radio advertisements and print brochures promoting Dixon and Crawford. Under D.C. election law, the money spent can exceed the maximum allowed to each candidate, but the extra political effort must be done independently of the respective campaigns.

Dixon is chiefly opposed in the chairman's race by councilman Douglas E. Moore, a vociferous opponent of the Board of Trade who likes to castigate it for supporting Dixon.

Dixon's campaign manager, Vivien Cunningham, said she was "delighted" about the board's proposed radio ads for Dixon, saying, "We need all the exposure we can get."

She said that, although Dixon has raised $86,000 so far, his campaign only has enough money for radio ads in the last week of the campaign.