WASHINGTON — U.S. Air Force Secretary Michael Donley will step down June 21, ending a nearly five-year run as the top civilian official in the service.

“It’s been an honor and a privilege to serve with our Air Force’s great Airmen,” Donley said in an Air Force press release. “Their accomplishments have been nothing short of impressive, and I’m humbled to be a part of this team. The Air Force has been a way of life for so much of my career, I know it will be bittersweet to say farewell.”

Donley took office in October 2008, making him the last service secretary appointed by President George W. Bush. An Air Force spokeswoman said Donley “intends to return to private life and give attention to his family and personal affairs” when he leaves the government. The spokeswoman added that Donley had been thinking about the move “for some time.”

Carol DiBattiste and Sheila Cheston, lawyers who served in senior Pentagon posts during the administration of President Bill Clinton, reportedly are two of the candidates to become Air Force secretary.

DiBattiste is general counsel and chief administrative officer of online retailer Geeknet. She served as Air Force undersecretary from 1999 to 2001.

Cheston is a corporate vice president and general counsel for Northrop Grumman and served as Air Force general counsel from 1995 to 1998.

In recent weeks, a new front-runner has emerged, according to a source: Deborah Lee James, executive vice president for communications and government affairs at SAIC. James, who served as assistant secretary of defense for reserve affairs from 1993 to 1998, also has Capitol Hill experience, having served as a staffer on the House Armed Services Committee. That background could benefit a service that has seen strained relations with Congress in recent years. A call to her office was not returned by publication date.

Whit Peters, who served as secretary of the Air Force during the Clinton era, also has been mentioned as a potential nominee. However, sources say that the administration of President Barack Obama would prefer that the next secretary be female. Sheila Widnall, who served as Air Force secretary from August 1993 to October 1997, is the only woman to serve as a secretary of a military service.

End of an Era

Donley’s run as secretary, one of the longest tenures in Air Force history, has been one of transition for the service, which has shifted focus from operations in Iraq and Afghanistan toward the Pacific.

He also oversaw a dramatic reduction in the number of aircraft active in the service and was forced to confront a series of sexual assault scandals.

“He clearly presided over a period of strategic change,” Rebecca Grant, president of IRIS Research, said.

Asked to identify the defining moments of Donley’s time in office, Grant highlighted what she called the low and high points.

The low point, Grant said, was in April 2009, when Donley co-authored a piece in The Washington Post supporting the decision to end production on the F-22 Raptor fighter jet. The high point was more recent, when Donley successfully entered the new long-range bomber as a program of record.

“He deserves a lot of credit for making that happen,” Grant said. “We won’t see the new bomber for some time, but no one can question the amount of personal effort he put into that and the importance he placed on that as vital for the national defense and the Air Force.”

As Donley prepares to leave, he is trying to ensure everything is in order for his successor. The service took a step forward April 23 by announcing that MITRE executive Bill LaPlante has been selected to fill the role of principal deputy assistant secretary for acquisition and management, which had been vacant since March 2012.

However, the big role to fill still remains head of acquisitions, which has been vacant for the majority of Donley’s term.

“The real gap up there is the lack of an acquisition executive,” Grant said. “It’s really unfortunate that they haven’t added another talented team member to run it. They haven’t even nominated anyone. That shouldn’t happen.”