When a historian wrote an essay the other day warning that the election of former President Donald J. Trump next year could lead to dictatorship, one of Mr. Trump’s allies quickly responded by calling for the historian to be sent to prison.

It almost sounds like a parody: The response to concerns about dictatorship is to prosecute the author. But Mr. Trump and his allies are not going out of their way to reassure those worried about what a new term would bring by firmly rejecting the dictatorship charge. If anything, they seem to be leaning into it.

If Mr. Trump is returned to office, people close to him have vowed to “come after” the news media, open criminal investigations into onetime aides who broke with the former president and purge the government of civil servants deemed disloyal. When critics said Mr. Trump’s language about ridding Washington of “vermin” echoed that of Adolf Hitler, the former president’s spokesman said the critics’ “sad, miserable existence will be crushed” under a new Trump administration.

Mr. Trump himself did little to assuage Americans when his friend Sean Hannity tried to help him out on Fox News this past week. During a town hall-style meeting, Mr. Hannity tossed a seeming softball by asking Mr. Trump to reaffirm that of course he did not intend to abuse his power and use the government to punish enemies. Instead of simply agreeing, Mr. Trump said he would only be a dictator on “Day 1” of a new term.

“Trump has made it crystal clear through all his actions and rhetoric that he admires leaders who have forms of authoritarian power, from Putin to Orban to Xi, and that he wants to exercise that kind of power at home,” said Ruth Ben-Ghiat, author of “Strongmen: Mussolini to the Present,” referring to Vladimir V. Putin of Russia, Viktor Orban of Hungary and Xi Jinping of China. “History shows that autocrats always tell you who they are and what they are going to do,” she added. “We just don’t listen until it is too late.”