Stephanie Grisham, United States First Lady Melania Trump’s chief of staff, says she is resigning effective immediately.
A longtime associate of Mrs Trump, Grisham was also a former White House spokeswoman.
She said it had been an honour to serve the Trump administration.
Grisham gave no reasons for her unexpected move.
It remained unclear whether her departure was related to the storming of the Capitol by supporters of outgoing president Donald Trump.