Melissa Harris-Perry said she was refusing to go on the MSNBC show she hosts this Saturday, following several weeks of pre-emptions and what she described as a loss of editorial control.

In an email sent to people she works with this week, which was obtained by The New York Times, Ms. Harris-Perry said that her show had effectively been taken away from her and that she felt “worthless” in the eyes of NBC News executives.

“Here is the reality: Our show was taken — without comment or discussion or notice — in the midst of an election season,” she wrote. “After four years of building an audience, developing a brand and developing trust with our viewers, we were effectively and utterly silenced.”