As Sen. Bernie Sanders (I-Vt.) has become the front-runner in the Democratic presidential primary, several MSNBC hosts and contributors have had some unfavorable things to say about the socialist — and the Sanders campaign is getting fed up.

Sanders campaign manager Faiz Shakir has grown increasingly frustrated with the tone of MSNBC's coverage toward the candidate and his supporters (the so-called "Bernie Bros"), and is concerned that because MSNBC is so influential on the left, it is hurting the perception of Sanders as an electable candidate with a chance to beat President Donald Trump in November.

"You can feel the disdain they have for Bernie Sanders's supporters," Shakir told Vanity Fair. "It's a condescending attitude: 'Oh, they must not be that intelligent. They're being deluded. They're being conned. They're all crazy Twitter bots.' My view is that there's a bit of detachment from MSNBC and the people who this campaign gets support from. It feels like they're covering progressives from an elitist perspective."

MSNBC's coverage has been so bad, in Shakir's opinion, that Sanders has gotten "more fair" coverage from Fox News — a conservative-leaning outlet that obviously holds a general belief that a socialist administration is the worst possible outcome of the 2020 election.

"Fox is often yelling about Bernie Sanders' socialism, but they're still giving our campaign the opportunity to make our case in a fair manner, unlike MSNBC, which has credibility with the left and is constantly undermining the Bernie Sanders campaign," Shakir said.

Perhaps the most aggressive Sanders opponent on MSNBC has been host Chris Matthews, who has had some spectacular rants about Sanders and socialism in recent weeks.

"I have my own views of the word socialist and I'd be glad to share them. … They go back to the early 1950s," Matthews said after the New Hampshire primary debate. "I have an attitude about them. I remember the Cold War. I have an attitude towards [Fidel] Castro. I believe if Castro and the Reds had won the Cold War there would have been executions in Central Park and I might have been one of the ones getting executed. And certain other people would be there cheering, okay?"