Why Karoline Leavitt might be impossible for Trump to replace

Donald Trump hardly needs anyone else to serve as his mouthpiece.

The most clamorous president in modern history always gets his message out — in a daily riot of online posts, interviews and rancor with reporters.

The departure of a press secretary therefore might seem like a trifle to the messenger in chief. But the exit of Karoline Leavitt, announced Wednesday, represents a significant personal and political loss. The vacuum she'll leave will emphasize her role as a vital member of the president's brain trust.