In plucking Schadlow to succeed Powell, McMaster is making a switch that brings a longtime colleague with a rare academic background into President Donald Trump’s West Wing. Schadlow holds a doctorate from the Johns Hopkins Nitze School of Advanced International Studies. The last West Wing aide who went by “Dr.” was former adviser Sebastian Gorka, whose degree came from a little-known institution, Corvinus University in Budapest.

McMaster, a three-star Army general, has known and worked with Schadlow — whose background is in research, not government — for close to a decade.

But Powell’s departure deprives McMaster of a close ally known for her unparalleled network of relationships both inside and outside the West Wing, according to White House aides and outside advisers.

That threatens to leave McMaster, who has struggled to overcome a rocky relationship and general difficulty communicating with Trump, more isolated in the West Wing.

“H.R. will lose on administration intel, and ties to some very key officials,” said one outside adviser close to the White House, noting that Powell’s close bonds with Ivanka Trump, Jared Kushner and the president himself have benefited by-the-book McMaster, who has had trouble learning how to schmooze with Trump.

A former official in the George W. Bush administration who also worked in the State Department under Condoleezza Rice, Powell served as a guide and support for McMaster, an active-duty military officer, in the chaotic Trump White House.

But given the loss of Powell, outside advisers to the White House said they saw Schadlow’s promotion as a positive move for an administration that at times has struggled to recruit experience and talent. The post, which will now by occupied by someone widely respected in her field, was in the early days of the administration held by a former Fox News commentator, K.T. McFarland.

“I’ve known Nadia for years,” said Elliott Abrams, a neoconservative foreign policy expert who served in the George W. Bush administration. “She has a wide and deep knowledge of national security issues, both diplomatic and military.”

In her recent book, “War and the Art of Governance,” for instance, Schadlow outlines a historical argument for why military leaders should factor in the political and economic reconstruction of states before entering into any armed conflict abroad.

Powell pushed hard for Schadlow to succeed her in the post after she decided months ago that she planned to leave the administration around the one-year mark, according to people familiar with the discussions. Often the only woman in the room during national security meetings and in the Situation Room, Powell made it clear that it should be a priority to keep a woman in the high-level post after her departure.

Powell’s replacement, multiple White House officials said, has been lined up and ready to roll out since the New Year, and Schadlow’s colleagues on the National Security Council have been informed about her impending promotion. But the White House has delayed making any official announcement about the job, putting Schadlow in an unexplained, temporary state of limbo.

That mirrors the current state of many high-level West Wing positions, where new staffers are already functioning in their roles and occupying new offices, with no official sign-off or rollout.

Former White House lawyer Jim Carroll, for instance, has been operating as the de facto deputy chief of staff since his predecessor, Kirstjen Nielsen, was confirmed as secretary of homeland security in December, even working out of her old office. But the White House has yet to make an announcement or officially name him to the post.

The government shutdown, which began Friday night at midnight, does not affect staffers on the NSC.

White House press secretary Sarah Huckabee Sanders and NSC spokesman Michael Anton did not respond to requests for comment about Schadlow or whether chief of staff John Kelly has signed off on the pick.

In the interim, Powell took steps to ease the transition.

Over the past few months, she introduced Schadlow to every member of the Senate Foreign Relations Committee and Cabinet. In her role as lead writer of the National Security Strategy, a document that serves as a blueprint for the White House’s “America First” foreign policy outlook, Schadlow also sat down with every member of the Cabinet for briefings and traveled to Aspen, Colorado, with McMaster last summer to present an early version of the plan to the Aspen Security Group.

But Schadlow is expected to be a very different partner for McMaster.

While Powell was known for keeping a hand in personnel decisions, trip planning and working as part of Kushner’s close-knit team dedicated to Middle East peace efforts, Schadlow’s past research has focused on Russia and Europe.

Where Powell also traveled regularly with the president aboard Air Force One, forging a personal bond with him and even being short-listed for the position of chief of staff, Schadlow has had limited interactions with the commander in chief, outside of briefing him on the National Security Strategy.

Powell has also worked closely and traveled with Defense Secretary James Mattis, CIA Director Mike Pompeo and Treasury Secretary Steven Mnuchin. Schadlow comes to the position with a preexisting relationship with Mattis — but as a relative newcomer to the other major players in Trumpworld.

“These roles are always defined by the person who fills them,” said one former national security official, noting that Schadlow is more of a foreign policy scholar-wonk in the mold of Avril Haines, the first female deputy national security adviser, who served in the Obama administration.

“These jobs are blank slates, not statutorily defined jobs,” the former official added. “The personalities really make a difference.”