Arlington Republican Committee Chairman Jade West, who has presided for four years over a party caught in conflict between conservatives and moderates, is resigning her post.

West could not be reached for comment last night, but her husband, Ray Lajeunesse, himself a conservative force in the party, confirmed her resignation in a telephone interview. He said it would be effective upon selection of a successor, probably at the committee's April 12 meeting.

West's decision, announced in letters mailed yesterday to committee members, surprised county Republicans who are beginning to prepare for fall election campaigns. The party's canvass, a local primary to select county and state candidates, is set for May 17 with candidates' filing deadline in two weeks.

Many moderate county Republicans were critical of the party's leadership after last November's election when Arlington County Board Chairman Stephen H. Detwiler lost a reelection bid, and only one GOP candidate ran, unsuccessfully, in the three House of Delegates races.

A Republican associate of West, who asked that his name not be used, said last night he believed intra-party controversy had no bearing on West's decision. Her resignation, the associate said, appeared to be more the result of "burn-out" from trying to juggle her fulltime job with the U.S. Senate's Republican Steering Committee and the chairmanship of the county organization.

"I think that she just decided that, in good faith, she can't handle both jobs," he said.