Defense News reports that "in an unprecedented move, US President Barack Obama has appointed Christine Fox, the Pentagon's former chief program and budget analyst, to serve as acting deputy defense secretary while the search continues for a candidate to fill the position on a full-time basis, defense sources said."
"When she replaces Ash Carter, who steps down Wednesday after two years on the job, she will become the senior-most woman to hold a DoD post. After leaving the Pentagon in June she became a senior adviser to the Johns Hopkins Applied Physics Laboratory, but remained an unpaid consultant to Carter, allowing her to keep current on DoD issues."
"Since the Senate confirmation process typically takes months, it is highly unlikely a replacement would be in place before the end of the year. Bringing back Fox allows other DoD senior officials to remain in their roles at a pivotal time as the Pentagon develops its FY '15 budget and as even steeper defense spending cuts loom and launches the latest Quadrennial Defense Review — in which she will play an integral role."