MSNBC, which significantly trails Fox News and CNN in ratings, is in the midst of an overhaul, pivoting away from its left-leaning identity toward hard news in the daytime hours. Ms. Harris-Perry had been the host of her show, which focused on issues like racism and social justice, since 2012.

On Friday, she went public with an email that she sent earlier that week to staff members in which she complained that the NBC News chairman, Andrew Lack, and Phil Griffin, the president of MSNBC, were letting her twist in the wind.

“I will not be used as a tool for their purposes,” she wrote. “I am not a token, mammy, or little brown bobble head. I am not owned by Lack, Griffin, or MSNBC. I love our show. I want it back.”

She later explained in an interview she did not believe that her lack of airtime was because she was black.

When she was in Des Moines and Mr. Melber was hosting from New York, Ms. Harris-Perry said she felt “like a guest” on her show. It was the first bad sign for what she would call a “painful” four-week stretch. She wanted to host the show from Iowa, and other primary states, but she was told by network executives that there were “insufficient resources” to allow that to happen, she said.

The following week, on Super Bowl Sunday, she said she planned to discuss Beyoncé’s new video, “Formation,” and how it addresses race, but was encouraged to focus on the election instead. She wound up discussing the video anyway but as she did, video of Jeb Bush and Chris Christie rallies in New Hampshire appeared in a box, a notable juxtaposition for a network that is now emphasizing round-the-clock election coverage.

It was the last time she would appear on MSNBC. Her show was pre-empted each of the next two weeks. “The branding was taken, editorial control was taken and I was no longer invited to host the show,” she said in the interview on Friday.