Trump's official Twitter account retweeted a quote from an account under Mussolini's nickname, Il Duce, which even has as its profile photo a portrait of the famously bald dictator with Trump's wispy hair photo-shopped onto his hairless pate.
The quote read: “It's better to live one day as a lion than a thousand years as a sheep,” a saying often attributed to Mussolini, who was fond of the expression and used it in a 1922 speech.
Journalism professor Christian Christensen suggested that the tweet was just another extension of Trump's right-wing views, which include banning Muslims and building walls to keep out migrants.
#MakeAmericaGreat (updated):— ChristianChristensen (@ChrChristensen) February 28, 2016
1. Build wall
2. Ban Muslims
3. Crush China
4. Deport Megyn Kelly
5. RT Mussolini
6. Get aide to explain KKK
Other Twitter users mocked Trump for his lack of political nous, suggesting the tweet would do little to win him votes.
statistically speaking, you & I both know people who will vote for the "Mussolini had interesting quotes" guy https://t.co/tCilT0LBp0— The Mountain Goats (@mountain_goats) February 28, 2016
When asked about the retweet, Trump told NBC news that he had known the expression was a Mussolini quote before he shared it from his account.
“I know who said it. But what difference does it make if it's Mussolini or anybody else?” Trump asked.
He also said that while he didn't want to be associated with the Fascist dictator, he did want to be associated with “interesting quotes”.
“I have almost 14 million people between Instagram, Facebook and Twitter, and all of that,” he continued.
“We do interesting things, and I sent it out. And certainly, hey, it got your attention, didn't it?”
It later emerged that the retweet had been part of a ploy led by American journalist Ashley Feinburg, who had been trying to see if Trump would retweet Mussolini for months.
Feinburg created a robotic twitter account in November which was programmed to send Mussolini quotes to Trump's account.
The idea was that Trump would eventually retweet one - a theory that proved to be correct.
On Sunday, after 2,000 tweets had already been sent to his account, he finally retweeted Mussolini.
The incident is not the first time that association with Fascism and far-right groups has created problems for Trump.
Last week, ex-Ku Klux Klan leader David Duke – who was expelled from Italy in 2013 for his extremist views – publicly endorsed Trump's bid to become the Republican presidential nominee.
In January, Anne Frank's stepsister, Eva Schloss, told reporters in Washington that Trump was “acting like another Hitler by inciting racism.”