Kathryn Wheelbarger, one of the Pentagon’s most prominent and respected policy officials, is resigning after three years in the job.
She is quitting at a time when critics have accused President Donald Trump of prioritising perceived “loyalists” for top national security posts, Reuters reported.
Wheelbarger, who is highly regarded by national security experts in Trump’s Republican Party and among Democrats, did not explain the reasoning for her departure in her resignation letter.
She had been named by the White House on Feb. 13 to a senior intelligence position.
But in a surprise move last week, the White House instead announced plans to nominate Bradley Hansell.
Hansell, a former special assistant to Trump, will become deputy undersecretary of defense for intelligence.
Both current and former U.S. officials accused the White House of passing over Wheelbarger because of her past work with the late Republican Senator John McCain, a fierce Trump critic.
McCain also chaired Senate Armed Services Committee.
Wheelbarger handled the committee’s intelligence portfolio and was well regarded by Congress.
“It looks like she failed the loyalty test somehow,” said one former U.S. official, speaking on condition of anonymity.
A congressional source said it was disappointing that the Trump administration did not recognize “one of its greatest assets.”
“She was one of the few really thoughtful, compelling voices that people really seemed to respond to,” the congressional source said, speaking on condition of anonymity.
In her letter, Wheelbarger said she trusted her colleagues would “continue to be guided by the U.S. Constitution and the principles of our founding, which ensure both our security and our freedom.”
The letter said her resignation would be effective from July 4.