Far-left former MSNBC host Keith Olbermann challenged fellow liberal Stephen Colbert to speak out against his employer, CBS, hiring Trump administration official Mick Mulvaney as an on-air contributor. 

Mulvaney, who served as President Trump’s acting chief of staff and Office of Management and Budget director, was added to CBS News’ lineup of political analysts this week. Olbermann, who loathed Trump so much that he walked away from an ESPN gig for a YouTube show devoted to bashing him, feels "The Late Show" host should speak up. 

Keith Olbermann challenged fellow liberal Stephen Colbert to speak out against CBS for hiring Trump administration official Mick Mulvaney as an on-air contributor.  (Photo by Taylor Hill/FilmMagic)

Keith Olbermann challenged fellow liberal Stephen Colbert to speak out against CBS for hiring Trump administration official Mick Mulvaney as an on-air contributor.  (Photo by Taylor Hill/FilmMagic)

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"So where is @StephenAtHome Colbert on his company putting @MickMulvaney on their news? And don't say ‘he can't be expected to be critical of CBS’ - that it IS @CBSNews makes it even more mandatory that he say something," Olbermann tweeted

Colbert, known for being obsequious toward Democratic politicians, is also a staunch critic of Trump and members of his administration.

CBS did not immediately respond to a request for comment from Fox News Digital. 

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Stephen Colbert’s newest colleague is former Trump administration official Mick Mulvaney.

Stephen Colbert’s newest colleague is former Trump administration official Mick Mulvaney. (CBS)

It appears Olbermann isn’t the only liberal peeved over CBS’ latest hire. The Washington Post reported on Wednesday that the decision to add Mulvaney has drawn "backlash" internally and obtained a recording of CBS News’s co-president Neeraj Khemlani justifying the decision to staffers. He revealed CBS honchos expect Republicans to prevail during the upcoming midterm elections and want on-air pundits who have access to the GOP. 

"If you look at some of the people that we’ve been hiring on a contributor basis, being able to make sure that we are getting access to both sides of the aisle is a priority because we know the Republicans are going to take over, most likely, in the midterms," Khemlani said, according to the Post.

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"A lot of the people that we’re bringing in are helping us in terms of access to that side of the equation," Khemlani added. 

Mulvaney previously served in the U.S. House of Representatives as a congressman representing South Carolina’s fifth district and was U.S. special envoy for Northern Ireland. He will serve as an analysis across CBS News platforms.