In 2017, Patterson co-wrote an op-ed for The Federalist website blaming mass killings on immigrants who failed to “assimilate” into American culture. The column came out days after an immigrant from Uzbekistan who was inspired by ISIS allegedly drove a truck into cyclists and runners in lower Manhattan, killing eight and injuring a dozen more.

“One explanation for the rise in terrorist behavior in the United States is the insidious and significantly difficult-to-pinpoint problem of failure to assimilate into an adopted culture,” Patterson and A.D.P. Efferson wrote. “By growing evidence, promoting ‘multiculturalism’ is a major culprit. We certainly don’t discount the influence of ISIS’ ubiquitous propaganda, but to be compelling there must be a willing mind.”

The authors continue: “Multiculturalism is the antithesis of what the United States stands for and the foundational thinking of our founding fathers that sustains America as its own unique society.

“We citizens welcome legal immigrants with the assumption they come of their own free will. That means they come to accept living in the United States with our laws and our culture the way it is, not the way they might want to change it.”

Patterson did not return multiple messages asking for comment. A spokesperson for the company where he works, SMA Inc., declined to comment, as did the Pentagon and the White House.

Patterson would have been the principal deputy undersecretary of Defense for Personnel and Readiness, effectively the No. 2 for Matthew Donovan, who’s performing the duties of the undersecretary of Defense for Personnel and Readiness.

Donovan’s job is to advise the Defense secretary and his deputy on readiness, health issues, training and personnel matters. That includes “equal opportunity, morale, welfare, recreation, and quality of life matters,” according to the DoD. The principal deputy job, for which Patterson was nominated, would oversee those areas as well.

Patterson previously served in the Pentagon during the Bush administration, including as the principal deputy undersecretary in the comptroller’s office. An Air Force pilot who served in Vietnam, Patterson retired with the rank of colonel in 1993.

Morning Defense The latest news in defense policy and politics. Sign Up Loading By signing up you agree to receive email newsletters or alerts from POLITICO. You can unsubscribe at any time. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.

The withdrawal comes amid a raft of senior departures at the Pentagon. Those include Navy Secretary Richard Spencer; Jimmy Stewart, the acting personnel chief; Randall Schriver, the top Indo-Pacific official; Kari Bingen, the department’s No. 2 intelligence official; and DARPA director Steven Walker.

Defense Secretary Mark Esper’s chief of staff, Eric Chewning, also left last month.

The vacancies have forced serving Pentagon officials to become either acting or “performing the duties of” for a variety of roles. Donovan himself is performing the duties of the top personnel chief. His confirmed job was that of Air Force undersecretary, but he took on the new role when Stewart, who was also performing the duties of the personnel role, left in December.

Robert Wilkie originally had the personnel job, but left it in March 2018 to be the secretary of the Veterans Affairs Department.

Jacqueline Feldscher contributed to this report.