Jack Keeney (photo by Ryan J. Reilly / Main Justice).

Put this one in the category of Big Shoes to Fill: The Justice Department on Wednesday posted an advertisement ^[1] for a job that has been occupied — and frequently transcended — by the same prosecutor for 37 years.

That prosecutor, John “Jack” Keeney, one of the longest-serving federal employees in U.S. history, will retire in ^[2] September after nearly 60 years at the department.

Since 1973, he has been Deputy Assistant Attorney General in the Criminal Division, a coveted position that is expected to draw more applications than any other division vacancy in this administration.

Keeney, now in his 80s, is widely regarded as among the finest lawyers the Criminal Division has ever produced. He has won every department award worth winning. A building is named in his honor. The head of the Criminal Division, Lanny Breuer, once referred to Keeney as “one of our most revered forefathers.”

That’s a lot to live up to.

“It’s probably impossible to plug that hole,” Breuer said in an interview. “The goal will be to reach out to find a person of gravitas and a person of great judgment, a person who is a great patriot.”

Keeney’s replacement will have oversight of the Office of Enforcement Operations, the unit that evaluates and approves the department’s use of surveillance tools, and the Public Integrity Section, which handles high-profile public corruption prosecutions. The job also has policy and legislative dimensions.

That’s Keeney’s brief on paper. But has played a much larger role, as ambassador for the Criminal Division and its institutional knowledge. His close friend David Margolis, an Associate Deputy Attorney General who has clocked 45 years at the department, carries a similar torch in the management office.

“They’re not going to replicate Mr. Keeney,” Breuer said of Keeney’s successor. “But they will be at the right time in their lives and have the right skill set to carry forth what he did.”