Former Alexandria prosecutor William L. Cowhig has decided not to seek reelection to the office he left under fire in January, an aide announced yesterday.

"Mr. Cowhig has decided not to run again. He had just been weighing that possibility, and now he has decided not to run again," said Mary Ann (Sam) Pastorek, a Cowhig aide.

Pastorek's statement came one day after the Alexandria Democratic Party tabled without a vote an unprecedented resolution urging Cowhig not to seek office agian in a party primary. The party tabled the resolution Monday night after it was told that Cowhig had decided not to run.

His decision marks the apparent end to the political career of the man who has been Alexandria's elected chief prosecutor from 1973 untill his resignation three months ago. The resolution itself marked the first time the city's Democratic leadership had actively sought to repudiate one of the party's most popular Aexandria vote-getters.

"There was a feeding that it would not be good for the party" if Cowhig ran again, said J. Daniel O'Flaherty, chairman of the Alexandria Democratic Committee.

"It would be a disaster" if Cowhig ran again, said Bill Livingston, a lawyer and former chairman of the group. "There is no prood that he is gulity (of the corruption charges now under investigation), but with those circumstances, how could anyone-police, victims or the accused-have confidence in the office?" he asked.

Cowhig was acquitted in two highly publicized trials of bribery and illegal gambling charges related to bingo games in the city. He resigned his office when another illegal gambling in dictment was dropped. Currently a special prosecutor is investigating allegations that four years ago Cowhig solicited a sexual favor from the wife of a defendant, a charge Cowhig has denied. A local committee of the Virginia State Bar independently is reviewing the trial testimony with a view toward possible disbarment action against Cowhig. Additionally, a federal grand jury investigating corruption changes, has subpoened the records of an accountant who-testified on Cowhig's behalf.

Pastorek declined to comment yesterday on why Cowhig decided not to seek again the office he has called "my whole life." Cowhig, who two weeks ago startled politicians with his announcement he might run, could not be reached for comment.

The party resolution urging Cowhig not to run was made in response to letters from Cowhig asking influential Democrats fro advice. "We suggested he not seek office again," O'Flaherty said yesterday.

The motion to table the resolution without a vote was made by the current commonwealth's attorney, John E. Kloch who has announced he is running for the prosecutor's job.

Republican Barry Poretz has also announced his candidacy.