MSNBC's Joe Scarborough on Tuesday compared President Trump calling former White House aide Omarosa Manigault Newman a "dog" to Nazis referring to "Jews as rats."

"We've heard it said before and we've heard it discussed before about how tyrants and autocrats and, yes, fascists, communists, others, have used the language of dehumanization to justify, well, a movement away from democracy and a movement away from decent standards," Scarborough said on "Morning Joe.

Scarborough said Trump's rhetoric is comparable to that of fascists and communists, adding that the country is "a movement away from democracy and a movement away from decent standard" as a result.

Scarborough then said he had found an NPR article from 2011 that included an interview with author David Livingstone Smith, author of "Less than Human."

Citing the NPR story, Scarborough said: "During the Holocaust, Nazis referred to Jews as rats. In Rwanda, genocide was often justified, calling Tutsis cockroaches. Slave owners throughout history considered slaves subhuman animals.

He said that was one of the key takeaways from Smith's book "Less than Human," which argues it's important to describe dehumanization "because it opens the door for cruelty and genocide."

"Nobody is saying that Donald Trump is a Nazi," Scarborough said, "nobody is saying that he's Adolf Hitler in 1938, 1939, 1940, but you can see time and time again ... this is actually how dictators and tyrants open the door, and they do it by dehumanizing their political opponents."

Trump called Manigault Newman a "crazed, crying lowlife" in a tweet earlier Tuesday morning to his 53.8 million followers and praised White House chief of staff for "quickly firing that dog!"

The commentary comes as advance orders have vaulted Manigault Newman's new book, "Unhinged," to #5 on the best-seller list. Heavy media attention has centered around recordings the former "Apprentice" contestant has been sharing in interviews and leaked copies of the book.

The MSNBC host has argued Trump possesses autocratic characteristics on the program on multiple occasions in the past.

Scarborough, a former GOP congressman who left the party in 2017 because of Trump, once had a close relationship with the former real estate mogul and reality show star.

Trump appeared regularly on "Morning Joe" by phone as a candidate for generally friendly interviews that drew criticism from other media members for what they saw as free advertising for his campaign.

Scarborough and co-host Mika Brzezinski's relationship with Trump soured after he captured the GOP nomination in May 2016. Trump has not appeared on the morning program or the network in any capacity since that time.

This story was updated at 5:19 p.m.