WASHINGTON — After weeks of expectations that the Pentagon’s No. 3 official would be leaving the building, he has officially resigned.

Jay Gibson, the department’s first chief management officer, submitted his resignation this week, with an effective end date of Nov. 30. Come December, Lisa Hershman, the deputy CMO, will assume those responsibilities as the acting CMO until a replacement nominee can be confirmed.

“Mr. Gibson’s groundbreaking work as the first-ever DoD Chief Management Officer set conditions for the department’s reform initiatives,” Lt. Col. Joe Buccino, a Pentagon spokesman, said in a statement. “His efforts to streamline processes, establish the department’s Reform Management Group, and identify significant savings across the department will pay dividends in FY19.”

“Our commitment to bringing business reform to the department remains unwavering and will result in the increased lethality of our force,” Buccino added. “We appreciate his service to the Department and wish him continued success.”

That statement doesn’t touch on the reality of the situation — that Gibson was forced out of his position after less than nine months on the job, due to what has been described as underperformance after being specifically told to find cash savings inside the building that could be plowed back into military needs.

In early September, the Wall Street Journal reported that Gibson had been effectively fired from the position for a lack of performance. Sources around the Pentagon confirmed that situation to Defense News, and indicated the official announcement would come just days later.

Since then, sources say, Gibson was iced out of the building while the process worked itself out.