A committee has been formed to promote a Nov. 6 write-in campaign for Sen. Margaret C. Schweinhaut (D-Montgomery), the third such long-shot drive in the Washington suburbs begun on behalf of candidates defeated in the September primary.

Schweinhaut, who served 30 years in the Maryland General Assembly, said yesterday that she was not involved in formation of Citizens to Write In Schweinhaut and would not help in the campaign. But she stopped short of disavowing the effort.

"If they want to do something, they are free citizens," said Schweinhaut, who lost the primary in District 18 by an almost 2 to 1 ratio to Del. Patricia R. Sher (D-Mongomery). There is no Republican in the race.

Montgomery County Executive Sidney Kramer, after losing a close Democratic primary to veteran County Council member Neal Potter, has actively mounted a write-in campaign for the general election. In Prince George's County, Tommie Broadwater Jr. has said he is organizing a write-in campaign in District 24, where he lost the Democratic primary to Sen. Decatur W. Trotter.

In Montgomery, the Sher-Schweinhaut primary race was viewed as a referendum on the abortion issue because Sher supports abortion rights while Schweinhaut opposes abortion in most cases.

Yesterday, Sher said antiabortion advocates were behind the write-in campaign.

"They're using her for their issue," She said. "Why would they want to cause her further humiliation?"

One of the organizers, Mary Bowen, disputed Sher's assertion, saying that Schweinhaut supporters represent both political parties and both sides of the abortion issue.

"We know we've bitten off a big chunk, but if we did nothing, people would go to the polls and only Sher would be on the ballot," said Bowen, a Republican who lives in an adjoining district.