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(WASHINGTON) — Former President Donald Trump vowed this weekend to “root out” his political opponents, who he said “live like vermin” as he warned supporters that America’s greatest threats come “from within” — extreme rhetoric that echoes the words of fascist dictators like Adolf Hitler and Benito Mussolini, experts and Trump’s critics said.

A Trump campaign spokesman dismissed the backlash to his speech, at a Veterans Day rally in New Hampshire, but some historians said the parallels were alarming.

“To call your opponent ‘vermin,’ to dehumanize them, is to not only open the door but to walk through the door toward the most ghastly kinds of crimes,” writer and historian Jon Meacham said on MSNBC’s “Morning Joe.”

Speaking to a packed crowd inside Stevens High School auditorium in Claremont, New Hampshire, on Saturday, Trump, who is seeking a second term in the White House, said: “We will put America first and today, especially in honor of our great veterans on Veterans Day, we pledge to you that we will root out the communists, Marxists, fascists and the radical left thugs that live like vermin within the confines of our country.”

He accused these groups of doing anything “to destroy America and to destroy the American dream” and he went on to repeat his baseless claims of election fraud.

A major theme of the rally was “peace through strength,” and Trump boasted of his own leadership on the world stage in comparison to President Joe Biden.

“The real threat is not from the radical right. The real threat is from the radical left,” he told attendees, drawing shouts of agreement. “It’s growing every day, every single day. The threat from outside forces is far less sinister, dangerous and grave than the threat from within. Our threat is from within. Because if you have a capable, competent, smart, tough leader — Russia, China, North Korea, they’re not gonna want to play with us.”

Just before he took the stage on Saturday afternoon, Trump posted a similar message on his social media platform.

The comments received immediate pushback, both from critics who have long challenged Trump’s habit of attacking others with hyperbolic insults and from historians who said his latest remarks had an unsettling resemblance to those of infamous authoritarians.

“Please tell us if this reminds you of any earlier historical figure,” NBC’s presidential historian Michael Beschloss wrote on X.

“It doesn’t echo ‘Mein Kampf.’ This is textbook ‘Mein Kampf,'” Yale University professor Jason Stanley, author of “How Fascism Works,” said about Trump’s comments on MSNBC. Stanley was referring to a book published by Hitler before his rise to power.

“Trump’s comments are remarkably evocative particularly of Hitler’s rants against Marxists and socialists — Hitler also decried pro-democratic forces as Marxist,” Stanley told ABC News.

“In another regard, this is worse than Nazi propaganda,” he said. “Bear in mind that there was actually a communist anti-democratic threat in Europe in the 1920s and ’30s, and there is none in America today.”

In a statement, Trump spokesperson Steven Cheung rejected the comparisons to Hitler and Mussolini.

“Those who try to make that ridiculous assertion are clearly snowflakes grasping for anything because they are suffering from Trump Derangement Syndrome and their sad, miserable existence will be crushed when President Trump returns to the White House,” Cheung said.

At the Veterans Day rally, while talking about legal challenges he’s facing, Trump also floated the possibility of retribution against his political enemies if he returns to the White House, though he said, “I don’t want to do that.”

He again suggested that the charges he faces in four criminal cases were brought for political reasons, though prosecutors have defended their work. Trump has pleaded not guilty and denies all wrongdoing.

The Biden campaign, which has been ramping up their responses to Trump’s campaign trail activities, slammed his “vermin” rhetoric as championing “un-American ideas.”

“On a weekend when most Americans were honoring our nation’s heroes, Donald Trump parroted the autocratic language of Adolf Hitler and Benito Mussolini – two dictators many U.S. veterans gave their lives fighting, in order to defeat exactly the kind of un-American ideas Trump now champions,” said campaign spokesperson Ammar Moussa.

“Donald Trump thinks he can win by dividing our country. He’s wrong, and he’ll find out just how wrong next November,” Moussa said.

Last month, Trump faced outcry from critics when he said during an interview with The National Pulse, a right-wing website, that immigrants who are in the country without documentation are “poisoning the blood” of America. He repeated his longstanding claim that terrorists, criminals and those with mental illness are coming in through the borders.

A White House spokesperson in a statement to The Daily Beast at the time called the comment “abhorrent” and “dangerous,” saying, “The role of leaders is to bring people together; never to turn them against one another with divisive, self-serving poison.”

Republican National Committee Chairwoman Ronna McDaniel repeatedly refused to weigh in on Trump’s “vermin” comments when asked during her appearances on NBC and CNN’s Sunday news shows.

“I will say this: I know President Trump supports our veterans,” McDaniel said on “Meet the Press.”

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