MSNBC spent about six years building itself into a different kind of cable-news network, with a diverse cast of hosts, anchors and contributors. It has taken a matter of months for people to call that image into question.

The network on Saturday dropped host Melissa Harris-Perry after she walked off her program to protest a series of preemptions because of campaign coverage. Harris-Perry, an African American intellectual, effectively sealed her fate by issuing an email to her colleagues that implied the network had mistreated her because of her race.

Although MSNBC expressed shock and denied the allegation, its makeover from a network featuring liberal talk shows to one focused on breaking news has led to diminished roles for a number of nonwhite personalities.

Harris-Perry’s departure gave new life to gripes on social media about MSNBC’s racial composition. These included the hashtag #MSNBCSoWhite, an echo of the protests that surrounded the absence of minorities among the Oscars’ best-acting nominations.

People close to Harris-Perry compiled a list of names of those with minority backgrounds who’ve been dismissed or assigned to lesser roles in the past year. The list includes program hosts such as Al Sharpton, Alex Wagner and Joy Reid, and African American contributors and pundits such as Michael Eric Dyson , Touré , Karen Finney and Goldie Taylor. Three other African Americans who have appeared as panelists and pundits — Janet Mock, Dorian Warren and the Rev. Jacqui Lewis — now mostly appear on Shift by MSNBC, the network’s little-viewed digital channel.

In addition, MSNBC officials have signaled that José Díaz-Balart, who anchors a weekday morning slot, may be reassigned soon to make way for an expansion of “Morning Joe” or the addition of a program hosted by one of “Morning Joe’s” personalities. Diaz-Balart, who also anchors for NBC-owned Telemundo, is based in Miami, which complicates the logistics for MSNBC’s campaign coverage, which is directed out of New York.

MSNBC began moving away from liberal-oriented talk shows last year because of low ratings. The change started at about the same time as the arrival of a new chairman at NBC News, Andrew Lack, who oversaw the creation of MSNBC in 1996 during an earlier stint in the job.

The network’s emphasis on campaign reporting — it brands itself “the Place for Politics” — has led to some improvements in its ratings. However, its competitors have also experienced ratings gains, leaving MSNBC mired in third place behind cable news leaders CNN and Fox News.

The network’s evolution has sparked concerns among employees that MSNBC is pulling back not only on its staff’s diversity, but also in its commitment to points of view not often heard on cable news. Harris-Perry, for one, often offered a fiery take on racial relations, and frequently booked guests who appeared infrequently elsewhere, such as New Yorker writer Jelani Cobb and DeRay Mckesson, a young Black Lives Matter activist who is running for mayor of Baltimore.

“There are lot of people who are extremely frustrated by” the on-air changes, said one employee who asked not to be named because he’s not authorized to speak for the network. “When you look at the number of people of color who have disappeared, it definitely gets your attention.”

In interviews, MSNBC President Phil Griffin and Yvette Miley, the network’s senior vice president of talent and diversity, say they have not stepped back from the network’s commitment to presenting different faces and points of view.

“MSNBC has been a leader when it comes to diversity,” said Griffin.“We’re in transition now, but that doesn’t mean our commitment has changed. We’re rebuilding, but our principles are unwavering.”

To be sure, MSNBC hasn’t gone in only one direction. Its emphasis on breaking news has brought a diverse set of reporters to MSNBC, Griffin and Miley noted, thanks to greater contributions from NBC News journalists. This has resulted in more airtime for African American reporters such as Kristen Welker, Ron Allen and Trymaine Lee, among others.

At the same time, low Nielsen ratings have also led to the cancellation of programs hosted by Ronan Farrow, Ed Schultz, and Abby Huntsman, Krystal Ball and Ari Melber, all of whom are white.

But several people at the network noted that MSNBC continues to feature an all-white lineup during prime-time hours and that its signature daytime personality is anchor Brian Williams, who left “NBC Nightly News” amid scandal last year. Its makeover has also included a daily slot for “Meet the Press” host Chuck Todd. NBC News veteran Andrea Mitchell continues to host a daily program as well.