D.C. City Council member Jerry A. Moore Jr. (R-At-Large), backed by Democratic council members, announced yesterday that he would be a write-in candidate for an at-large council seat in the November general election.

Moore's long-awaited announcement followed a draft movement that began shortly after he lost to former school board member Carol Schwartz in the Sept. 11 Republican primary and has been building momentum in recent weeks.

Moore's write-in campaign makes the six-way race for two at-large council seats unusually complicated. Most observers expect incumbent John Ray (D-At-Large) to retain his seat easily. But the other seat, the one currently held by Moore and reserved for a minority party or independent candidate, seems up for grabs.

Democrats supporting Moore, a Republican, are pitted against other Democrats supporting Statehood Party candidate Josephine Butler. GOP nominee Schwartz's chief opponent is the same candidate she defeated in the Republican primary. And the other candidates, independent Brian Moore and Communist Party candidate Maurice Jackson, fear that too few people will pay attention to their campaigns.

Jerry Moore, a 15-year council veteran, said yesterday that the community is demanding he make another attempt to keep his seat.

"Sometimes, you never know the extent of how much you are appreciated until unexpected tragedy, crisis or death," Moore said during a press conference at the District Building. " . . . The thousands of persons who have signed petitions and the impressive cross-section of black and white leadership urging me to run clearly supersede the minority representation of voters in the Republican primary."

At his press conference, Moore -- wearing a dark blue suit with a red carnation in the lapel of his jacket -- said he would be an "enthusiastic write-in candidate." Later, at a campaign rally held last night at the Nineteenth Street Baptist Church, where Moore is pastor, he told reporters that he is a Republican, but plans to run a nonpartisan campaign.

"I'm just running as Jerry Moore unattached." he said. "One does not have to have a party designation."

Moore declined to respond to accusations that he is undermining the party primary process by conducting a write-in campaign after he lost a primary election.

Members of the Democratic State Committee had adopted a resolution Thursday night that criticized Democratic officials for supporting a write-in candidate who runs after losing in a party primary, and criticizing Democrats who vote for any candidate who does not support the Democratic presidential ticket -- a measure clearly aimed at the Democratic City Council members who support Moore.

Six Democrats on the council have pledged to use their influence or political organizations to help Moore get elected. Theodis R. (Ted) Gay, a state committee member who introduced the resolution, said he was concerned that Moore's action may "undermine the party primary process."

Schwartz said yesterday that Moore once promised to support her if she won the primary. She added that she was disappointed that he plans to run, but said that Moore's write-in campaign will not force her to change her strategy.

"We're talking about the integrity of the party process," said Schwartz. "For 15 years, it served him Moore well and he certainly didn't complain when it worked to his advantage for all those years. When the party process didn't work to his advantage he abandoned the process."

Write-in campaigns traditionally are viewed as difficult. Connie Mack Higgins, a Republican and the chairman of the committee to draft Moore, said yesterday that educating voters about how to write in a candidate's name will be the main concern of the Moore campaign.

Higgins is one of several voters who filed a lawsuit to prevent the D.C. Board of Elections and Ethics from enforcing a board rule prohibiting voters from using preprinted stickers bearing the name of a candidate to cast a write-in vote. A judge has not ruled on the lawsuit.

No one in the history of the City Council has ever won a seat through a write-in campaign, although three candidates, one an incumbent, have tried.

Former council member James Coates conducted a write-in campaign in 1976 after losing the Ward 8 primary race. The elections board allowed Coates to use stickers. He lost the council election but won one Advisory Neighborhood Commission (ANC) seat and was a runner-up in three other ANC races by way of write-in stickers intended for the council race.

In the Moore race, a Moore spokesman said, members of Mayor Marion Barry's political organization will work for Moore. Sources said that Moore viewed support from the mayor's organization as crucial to his decision to run.

Ivanhoe Donaldson, chairman of the Democratic State Committee, said yesterday that he has not decided whether he will support Moore. Donaldson, however, said that he disagreed with the state committee resolution criticizing any Democratic official who supports a write-in campaign for a candidate defeated in a primary.

The resolution, which also calls on "all Democrats to vote only for those candidates who support the national Democratic Party ticket," passed by a vote of 28 to 23.

"To me, it looked like the incumbent preservation act, all these City Council members saying we want Jerry Moore to remain," said Mark L. Plotkin, a member of the state committee. " . . . We don't feel Democratic officials should participate in a campaign for someone who casts a vote for Ronald Reagan."

Yesterday, City Council Chairman David A. Clarke sat beside Moore as he announced his candidacy and council member Polly Shackleton (D-Ward 3) added her name to the list of five Democratic council members who backed the write-in campaign from the beginning.