Donald J. Trump rose to power with political campaigns that largely attacked external targets, including immigration from predominantly Muslim countries and from south of the United States-Mexico border.
But now, in his third presidential bid, some of his most vicious and debasing attacks have been leveled at domestic opponents.
During a Veterans Day speech, Mr. Trump used language that echoed authoritarian leaders who rose to power in Germany and Italy in the 1930s, degrading his political adversaries as “vermin” who needed to be “rooted out.”
“The threat from outside forces,” Mr. Trump said, “is far less sinister, dangerous and grave than the threat from within.”
This turn inward has sounded new alarms among experts on autocracy who have long worried about Mr. Trump’s praise for foreign dictators and disdain for democratic ideals. They said the former president’s increasingly intensive focus on perceived internal enemies was a hallmark of dangerous totalitarian leaders.
Scholars, Democrats and anti-Trump Republicans are asking anew how much Mr. Trump resembles current strongmen abroad and how he compares to authoritarian leaders of the past. Perhaps most urgently, they are wondering whether his rhetorical turn into more fascist-sounding territory is just his latest public provocation of the left, an evolution in his beliefs or the dropping of a veil.
“There are echoes of fascist rhetoric, and they’re very precise,” said Ruth Ben-Ghiat, a professor at New York University who studies fascism. “The overall strategy is an obvious one of dehumanizing people so that the public will not have as much of an outcry at the things that you want to do.”
Mr. Trump’s shift comes as he and his allies devise plans for a second term that would upend some of the long-held norms of American democracy and the rule of law.
These ambitions include using the Justice Department to take vengeance on his political rivals, plotting a vast expansion of presidential power and installing ideologically aligned lawyers in key positions to bless his contentious actions.
Mr. Trump’s allies dismiss the concerns as alarmism and cynical political attacks.
Steven Cheung, a campaign spokesman, responded to criticism of the “vermin” remarks by saying it came from reactive liberals whose “sad, miserable existence will be crushed when President Trump returns to the White House.” Mr. Cheung did not respond to requests for comment for this article.
Some experts on authoritarianism said that while Mr. Trump’s recent language has begun to more closely resemble that used by leaders like Hitler or Benito Mussolini, he does not quite mirror fascist leaders of the past. Still, they say, he does exhibit traits similar to current strongmen like Viktor Orban of Hungary or Recep Tayyip Erdogan of Turkey.
Mr. Trump’s relatively isolationist views run counter to the hunger for empire and expansion that characterized the rule of Hitler in Germany and Mussolini in Italy. As president, he was never able to fully wield the military for political purposes, meeting resistance when he sought to deploy troops against protesters.
“It’s too simplistic to reference him as a neofascist or autocrat or whatever — Trump is Trump, and he has no particular philosophy that I’ve seen after four years as president,” said former Defense Secretary Chuck Hagel, a Republican who served in President Barack Obama’s cabinet after 12 years as a senator from Nebraska.
Still, Mr. Trump’s campaign style is “damn dangerous,” Mr. Hagel said.
“He continues to push people into corners and give voice to this polarization in our country, and the real danger is if that continues to bubble up and take hold of a majority of Congress and statehouses and governorships,” Mr. Hagel went on. “There must be compromise in a democracy because there’s only one alternative — that’s an authoritarian government.”
Mr. Trump has become increasingly unrestrained with each successive campaign, a pattern that parallels the escalating stakes for him personally and politically.
In 2016, he was a long-shot candidate with little to lose, and his broadsides were often paired with schoolyard taunts that drew laughs from his audiences. Four years later, Mr. Trump’s approach became angrier as he sought to cling to power, and his term ended in a deadly riot by his supporters at the Capitol.
This election cycle, Mr. Trump faces more pressure than ever. In part, his decision to open an early White House campaign was an attempt to shield himself from multiple investigations, which have since resulted in the bulk of the 91 felony charges he now faces.
Politically, Mr. Trump risks becoming a historic two-time loser. In the Republican Party’s nearly 168-year history, only one presidential nominee — Thomas Dewey — has lost two White House bids.
Mr. Trump’s attacks sweep from the highest echelons of politics to low-level bureaucrats whom he has deemed insufficiently loyal.
He has insinuated that the nation’s top military general should be executed and called for the “termination” of parts of the Constitution. If he wins back the White House, he has said, he would have “no choice” but to imprison political opponents.
He has tested the legal system with broadsides against the integrity of the judiciary, railing against prosecutors, judges and, more recently, a law clerk in his New York fraud trial as “politically biased” and “out of control.”
Crowds at Mr. Trump’s events have generally affirmed his calls to drive out the political establishment and to destroy the “fake news media.” Supporters do not flinch when he praises leaders like Mr. Orban, Xi Jinping of China and Vladimir V. Putin of Russia.
Standing amid nearly two dozen American flags at an Independence Day celebration in South Carolina in July, Mr. Trump promised retribution against Mr. Biden and his family.
“The gloves are off,” he said. The crowd unleashed a resounding cheer.
Supporters roared in approval when Mr. Trump called Democrats in Washington “a sick nest of people that needs to be cleaned out, and cleaned out immediately.”
While Mr. Trump’s fan base remains solidly behind him, his return to the White House may be decided by how swing voters and moderate Republicans respond to his approach. In 2020, those voters tanked his bid in five key battleground states, and dealt Republicans defeats in last year’s midterm elections and this month’s legislative contests in Virginia.
But Mr. Trump and his team have been energized by signs that such voters so far appear to be more open to his 2024 campaign. A recent New York Times/Siena College poll found Mr. Trump leading Mr. Biden in five of the most competitive states.
Mr. Biden has often sought to paint Mr. Trump as extreme, saying recently that the former president was using language that “echoes the same phrases used in Nazi Germany.” Mr. Biden also pointed to xenophobic remarks that Mr. Trump made last month during an interview with The National Pulse, a conservative website, in which he said immigrants were “poisoning the blood” of America.
“There’s a lot of reasons to be against Donald Trump, but damn, he shouldn’t be president,” Mr. Biden said at a fund-raiser in San Francisco.
Worries about Mr. Trump extend to some Republicans, though they are a minority in the party.
“He’s absolutely ratcheting it up, and it’s very concerning,” said former Gov. John Kasich of Ohio, who ran for the Republican presidential nomination in 2016 against Mr. Trump. “There’s just no limit to the anger and hatred in his rhetoric, and this kind of poisonous atmosphere has lowered our standards and hurts our country so much.”
Mr. Trump’s rise to power was almost immediately accompanied by debates over whether his ascendancy, and that of other leaders around the world with similar political views, signaled a revival of fascism.
Fascism is generally understood as an authoritarian, far-right system of government in which hypernationalism is a central component.
It also often features a cult of personality around a strongman leader, the justification of violence or retribution against opponents, and the repeated denigration of the rule of law, said Peter Hayes, a historian who has studied the rise of fascism.
Past fascist leaders appealed to a sense of victimhood to justify their actions, he said. “The idea is: ‘We’re entitled because we’ve been victimized. We’ve been cheated and robbed,’” he said.
Recent polls have suggested that Americans may be more tolerant of leaders who violate established norms. A survey released last month by the Public Religion Research Institute found that 38 percent of Americans supported having a president “willing to break some rules” to “set things right” with the country. Among Republicans surveyed, 48 percent backed that view.
Jennifer Mercieca, a professor at Texas A&M University who has researched political rhetoric, said Mr. Trump had wielded language as a chisel to chip away at democratic norms.
“Normally, a president would use war rhetoric to prepare a nation for war against another nation,” she said. “Donald Trump uses war rhetoric domestically.”