White House deputy national security adviser Andy Baker is leaving the administration in the coming weeks.Why it matters: Baker, who also served as national security advisor to Vice President Vance, was among the staffers most central to the administration's foreign policy and national security decision-making over the last 18 months.Baker was also personally involved in negotiations with Iran this year. Cliff Sims, who succeeded Baker as Vance's national security adviser earlier this summer, will continue in that role. Mike Needham will continue as White House deputy national security adviser."This has been an amazing journey. I'm proud of everything we've achieved and, of course, am incredibly grateful to the President, Vice President, and Secretary Rubio," Baker told Axios in a statement.Catch up quick: Baker served as a foreign service officer at the State Department several years ago and then joined then-Sen. Vance's team as a national security advisor.Between the lines: A source close to Baker said he wants to spend more time with his family and stayed on months longer than planned to ensure an orderly transition to Sims and Needham. What to watch: Baker is expected to work in the private sector with Robert O'Brien, who served as President Trump's fourth national security advisor during his first term. What they're saying: Baker's colleagues heaped praise on him."Andy is an exceptionally gifted, deeply thoughtful advisor who has served the President and me with distinction. He has been an indispensable member of our administration's national security team," Vance told Axios in a statement. Secretary of State Marco Rubio, who also serves as White House national security advisor, said Baker has been "an invaluable asset and key member of the President's national security team who has greatly advanced the America First agenda."Needham called Baker "a brilliant foreign policy mind and close friend."And Trump's special envoy Steve Witkoff said in a statement: "From day one, Andy has worked tirelessly to put America first and get deals done for the President around the world."