Republicans in Northern Virginia's 10th Congressional District deadlocked last night in their effort to select a new chairman, as the party's top officials and moderate leadership clashed with its most conservative wing.

The 10th District committee, with 14 voting members from Arlington, Fairfax and Loudoun counties, tied, 7-7, through four ballots and then adjourned in frustration. Fairfax State Del. Vincent F. Callahan, despite his stature as Virginia House minority leader and the endorsement of GOP 10th District Rep. Frank R. Wolf, could not win a majority in his race against conservative attorney and longtime Reagan supporter Raymond J. LaJeunesse Jr.

"We'll have to do some talking," sighed outgoing chairman Judy Shreve, who had hoped to relinquish the job last night. "I remain chairman until something happens."

Some members of the party's conservative wing supported Callahan, and both sides promised to unite behind the eventual winner. But the deadlock reflected a continuing and deep fissure between the conservative and moderate wings of Northern Virginia's Republican Party.

LaJeunesse, 39, has been active in the 10th District since his days as a young Republican and now works for the National Right to Work Foundation. He was supported by such conservatives as John S. Buckley, a former Virginia state delegate who now works for the National Tax Limitation Committee; William J. Olson, former Fairfax County party chairman whom Reagan appointed to the Legal Services Corporation board, and Jade West, the Arlington party chairman who is married to LaJeunesse.

Callahan was persuaded to say he would accept the chairmanship, although he said he would not campaign for it, after some Republicans said they feared LaJeunesse's conservatism would alienate voters and party workers. "There was a strong feeling that we want to have someone who can communicate with everyone and make sure we remain unified," said Shreve, who during her five years as chairman helped Wolf take the congressional seat away from Democratic Rep. Joseph Fisher in 1980 and win reelection this year.

The party chairman will be influential in directing party resources in 1983, when state legislators and supervisors in Arlington, Fairfax and Loudoun counties are up for election, and in the early jockeying for the 1984 presidential race.

Some Republican operatives predicted after the voting last night that Wolf now will try to use his influence to ensure the selection of a chairman he can work with, perhaps a third candidate not nominated last night.