In an unusually public flare-up, one of MSNBC’s television personalities clashed with the network on Friday in a dispute about airtime and editorial freedom and said she was refusing to host the show that bears her name this weekend.

The host, Melissa Harris-Perry, wrote in an email to co-workers this week that her show had effectively been taken away from her and that she felt “worthless” in the eyes of NBC News executives, who are restructuring MSNBC.

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

In a phone interview, Ms. Harris-Perry confirmed she would not appear on the show this weekend. She said she had received no word about whether her show, which runs from 10 a.m. to noon on Saturdays and Sundays, had been canceled, but said she was frustrated that her time slot had faced pre-emptions for coverage of the presidential election. She said she had not appeared on the network at all “for weeks” and that she was mostly sidelined during recent election coverage in South Carolina and New Hampshire. (She was asked to return this weekend.)