“After three and a half years as Deputy Commissioner, Acting Commissioner and, finally, as Commissioner, it is time at the age of 67, to step aside,” Crawford said in a memorandum to FDA staff.

Sources familiar with his departure said Crawford was asked to resign. Crawford's tenure was marked by increasing criticism of the agency by those who contended it had become more interested in politics than in its mission to protect consumers. Asked if he was forced to resign, HHS spokeswoman Christina Pearson declined to comment further, calling it a personnel issue.

Last month, morale at the agency plummeted when Crawford indefinitely postponed nonprescription sales of morning-after contraception over the objections of staff scientists who had declared the pill safe. FDA's women's health chief resigned.

Many FDA critics lauded Crawford's departure.

“The American consumer should shed no tears at Mr. Crawford's resignation," said Sen. Byron Dorgan, a North Dakota Democrat who voted against Crawford's confirmation. “The fact is, he took the side of the pharmaceutical industry and against consumers at virtually every opportunity.”

“In recent years, the FDA has demonstrated a too-cozy relationship with the pharmaceutical industry and an attitude of shielding rather than disclosing information,” said Sen. Charles Grassley, R-Iowa, who has spent 18 months investigating the agency.

Crawford was confirmed as head of the FDA by the Senate on July 18. President Bush nominated him for the position in February. He had managed the agency since he became acting commissioner in March 2004 following Dr. Mark B. McClellan's tenure as commissioner. Previously Crawford had served as deputy commissioner during 2002.