Angella Reid, appointed in 2011 by President Obama
That used to be a position that was non-political and they served through many administrations. I read a book out several years ago; “Upstairs at the White House” written by J.B. West that had been Chief Usher for 28 years through many presidencies.
Could very well be she turned out not to be so non-political, and was quite possibly a leaker to media and other politicians. That is my guess, a mole.