The White House backed candidate for the post of executive director of the Commodity Futures Trading Commission is the controversial former president of the Bay Area Rapid Transit system who came under the scrutiny of two San Francisco grand juries earlier this year over the handling of his expense accounts.

Elmer Cooper, who worked on the Carter campaign in Illinos from Auguest to November 1976, has been working as a consultant at the CFTC on chairman William T. Bagley's staff since March.

Commission sources say Cooper is the leading candidate for the executive director's job, but his appointment has been delayed by Civil Service Commission and other background checks.

Cooper was not charged with any wrongdoing following the completion of the grand jury investigation in January although he reimbursed BART for $2,338 in expenses for which he did not have documentation.

"He's been very open about the whole thing," a commission source said."He doesn't think he did anything wrong, he wasn't charged with doing anything wrong and he's a working professional in Washington to get on with his career."

San Francisco and Oakland newspapers published half a dozen accounts of Cooper's candidacynfor the CFTC post over the weekend. The articles were triggered by a recent Jack Anderson column on Cooper.

Bagley said yesterday that he hired Cooper at "the recommendation of a mutual friend in San Francisco" in March, along with three or four other persons, on special 90-day consultant ships.

In June, when the agency's acting executive director, Anthony MacDonald, announced his intention to resign, Cooper expressed interest in the job, Bagley said. "The White House called shortly afterward and expressed a strong interest in Cooper," he said.

At a meeting late yesterday, the five-member commission deferred any action on Cooper's status until "some future date," according to Bagley.

Commission sources said the White House has taken "a hands' off attitude" on Cooper since reports of the grand jury investigations circulated. "They're understandably nervous, especially in light of the Lance thing," one source said yesterday.