“Something bad is happening,” Donald Trump warned New Hampshire voters Tuesday night, casting suspicions on Muslims and mosques. “Something really dangerous is going on.”

On Thursday evening, his message was equally ominous, as he suggested a link between the shootings in San Bernardino, Calif., and President Barack Obama’s failure to say “radical Islamic terrorism.”

“There is something going on with him that we don’t know about,” Trump said of the president, drawing applause from the crowd in Washington.

The dark power of words has become the defining feature of Trump’s bid for the White House to a degree rarely seen in modern politics, as he forgoes the usual campaign trappings — policy, endorsements, commercials, donations — and instead relies on potent language to connect with, and often stoke, the fears and grievances of Americans.

The New York Times analyzed every public utterance by Trump over the past week from rallies, speeches, interviews and news conferences to explore the leading candidate’s hold on the Republican electorate for the past five months. The transcriptions yielded 95,000 words and several powerful patterns, demonstrating how Trump has built one of the most surprising political movements in decades, and, historians say, echoing the appeals of some demagogues of the past century.

Trump’s breezy stage presence makes him all the more effective because he is not as off-putting as those raging men of the past, these experts say.

The most striking hallmark was Trump’s constant repetition of divisive phrases, harsh words and violent imagery that U.S. presidents rarely use, based on a quantitative comparison of his remarks and the news conferences of recent presidents, Democratic and Republican. He has a particular habit of saying “you” and “we” as he inveighs against a dangerous “them” or unnamed other — usually outsiders like illegal immigrants (“they’re pouring in”), Syrian migrants (“young, strong men”) and Mexicans, but also leaders of both political parties.

At an event in Raleigh, N.C., on Friday evening, his voice scratchy and hoarse, Trump was asked by a 12-year-old girl from Virginia, “I’m scared — what are you going to do to protect this country?”

“You know what, darling? You’re not going to be scared anymore. They’re going to be scared. You’re not going to be scared,” Trump said, before describing the Sept. 11 terrorists as “animals” who sent their families back to the Middle East. “We never went after them. We never did anything. We have to attack much stronger. We have to be more vigilant. We have to be much tougher. We have to be much smarter, or it’s never, ever going to end.”

While many candidates appeal to the passions and patriotism of their crowds, Trump appears unrivaled in his ability to forge bonds with a sizable segment of Americans over anxieties about a changing nation, economic insecurities, ferocious enemies and emboldened minorities (like the first black president, whose heritage and intelligence he has all but encouraged supporters to malign).

“‘We vs. them’ creates a threatening dynamic, where ‘they’ are evil or crazy or ignorant and ‘we’ need a candidate who sees the threat and can alleviate it,” said Matt Motyl, a political psychologist at the University of Illinois at Chicago who is studying how the 2016 presidential candidates speak. “He appeals to the masses and makes them feel powerful again: ‘We’ need to build a wall on the Mexican border — not ‘I,’ but ‘we.’”

In another pattern, Trump tends to attack a person rather than an idea or a situation, like calling political opponents “stupid” (at least 30 times), “horrible” (14 times), “weak” (13 times) and other names, and criticizing foreign leaders, journalists and anchor babies. He bragged on Thursday about psyching out Jeb Bush by repeatedly calling him “low-energy,” but he spends far less time contrasting Bush’s policies with his own proposals, which are scant.

And on Friday night in Raleigh, he mocked people who reportedly did not contact the authorities with concerns about the California shooting suspects for fear of racial profiling.

“Can anybody be that dumb?” Trump said. “We have become so politically correct that we don’t know what the hell we’re doing. We don’t know what we’re doing.”

The specter of violence looms over much of his speech, which is infused with words like kill, destroy and fight. For a man who speaks off the cuff, he always remembers to bring up the Islamic State “chopping off heads.” And he has expressed enthusiasm for torturing enemies beyond waterboarding. Last month, after several men hit a Black Lives Matter protester at one of his rallies, Trump said, “Maybe he should have been roughed up.”

“Such statements and accusations make him seem like a guy who can and will cut through all the b.s. and do what in your heart you know is right — and necessary,” said Michael Kazin, a historian at Georgetown University, echoing the slogan that Barry Goldwater used in his 1964 presidential campaign.

Trump declined a request to be interviewed for this article.

These patterns of elevating emotional appeals over rational ones is a rhetorical style that historians, psychologists and political scientists placed in the tradition of political figures like Goldwater, George Wallace, Joseph McCarthy, Huey Long and Pat Buchanan, who used fiery language to try to win favor with struggling or scared Americans. Several historians watched Trump’s speeches last week, at the request of The Times, and observed techniques — like vilifying groups of people and stoking the insecurities of his audiences — that they associate with Wallace and McCarthy.

“His entire campaign is run like a demagogue’s — his language of division, his cult of personality, his manner of categorizing and maligning people with a broad brush,” said Jennifer Mercieca, an expert in U.S. political discourse at Texas A&M University. “If you’re an illegal immigrant, you’re a loser. If you’re captured in war, like John McCain, you’re a loser. If you have a disability, you’re a loser. It’s rhetoric like Wallace’s — it’s not a kind or generous rhetoric.”

“And then there are the winners, most especially himself, with his repeated references to his wealth and success and intelligence,” said Mercieca, noting a particular remark of Trump’s on Monday in Macon, Georgia. (“When you’re really smart, when you’re really, really smart like I am — it’s true, it’s true, it’s always been true, it’s always been true.”)

“Part of his argument is that if you believe in American exceptionalism, you should vote for me,” Mercieca said.

Trump has said he will tear into anyone who tries to take him on, and he presents himself as someone who is always right in his opinions — even prophetic, a visionary. He repeatedly insists that he alone predicted the rise of Osama bin Laden in 2001 (despite the fact that the bin Laden network had attacked two U.S. embassies and the USS Cole in the three years before). “I said, ‘We better be careful, that’s gonna happen, it’s gonna be a big thing,’ and it certainly is a big thing,” Trump has said of what he wrote about the al-Qaida leader in 2000.

It is the sort of trust-me-and-only-me rhetoric that, according to historians, demagogues have used to insist that they have unique qualities that can lead the country through turmoil. Trump often makes that point when he criticizes his Republican rivals, though he also pretends that he is not criticizing them.

“All of ‘em are weak, they’re just weak,” Trump said in New Hampshire on Tuesday of his fellow candidates. “I think they’re weak, generally, you want to know the truth. But I won’t say that, because I don’t want to get myself, I don’t want to have any controversies. So I refuse to say that they’re weak generally, OK? Some of them are fine people. But they are weak.”

© 2015 The New York Times Company