Lester Crawford (Yahoo photo)

WASHINGTON, Sept. 23 (Xinhuanet) -- US Food and Drug Administration (FDA) Commissioner Lester Crawford tendered his resignation on Friday, and President George W. Bush immediately announced his intention to name Andrew von Eschenbach to take his place.

    Crawford's resignation took effect immediately, and it was not known why he chose to leave less than three months after he was confirmed for the job.

    Crawford, who had worked in the agency on four separate occasions over 30 years, was confirmed by the Senate after servingas a longtime deputy and acting commissioner, when Health and Human Services Secretary Mike Leavitt assured Senate Democrats the FDA would act on over-the-counter sales of the morning after pill Plan B by Sept. 1.

    Crawford was under fresh attack in late August when the FDA indefinitely postponed a ruling on whether Barr Pharmaceuticals Inc. could sell the Plan B contraceptive without a prescription.

    Bush asked Eschenbach, director of the National Cancer Institute, to serve as acting FDA commissioner, the White House said in a statement.

    Bush intended to "designate Andrew von Eschenbach, of Texas, tobe acting commissioner of Food and Drugs at the Food and Drug Administration at the Department of Health and Human Services," the statement said. Enditem