Donald J. Trump leaned forward in his chair in the Capitol Hill hearing room, tossed aside his prepared remarks as too “boring” and told lawmakers on an October day in 1993 that granting gaming licenses to Native American reservations in New York, New Jersey and Connecticut — a threat to Mr. Trump’s own casinos — would be a big mistake.
There were criminal elements at work in the reservations, he warned ominously and without evidence. “It will be the biggest scandal ever, the biggest since Al Capone,” Mr. Trump said.
Then he went a step further and cast doubt on the Native Americans themselves. “If you look at some of the reservations that you’ve approved, that you, sir, in your great wisdom have approved,” Mr. Trump told Representative George Miller, a California Democrat who has since retired, “I will tell you right now: They don’t look like Indians to me.”
For decades, President Trump has sown distrust in almost everything he touches. From Native Americans and business competition in New York to President Barack Obama’s birthplace to America’s intelligence agencies to the special counsel investigation he calls the “Russia hoax,” Mr. Trump’s goal has been to undermine the opposition, rely on conspiracy theories to discount any evidence that might discredit him — and, above all, leave people uncertain about what to believe.
In the last week alone, Mr. Trump has reposted messages asserting that the real death toll from the coronavirus was only around 9,000 and not 185,000, talked cryptically about a planeload of “thugs” in black uniforms flying to Washington to disrupt the Republican National Convention and asserted without a shred of evidence that his Democratic opponent, former Vice President Joseph R. Biden Jr., was “on some kind of an enhancement” drug.
People who have known the president for years say one of his most sustained assaults, on the integrity of the 2020 election, is straight from his New York tactics.
The president has said with no evidence that “millions and millions of ballots” have been sent to dead people and dogs and cats. He has floated the possibility of postponing the election because of the coronavirus pandemic — an idea swiftly shot down by his own party. And at the opening of the Republican National Convention in Charlotte, N.C., he asserted that mail-in voting “is going to be one of the greatest scams.”
Mr. Trump’s critics point out that as president he has never had more power to shape public opinion and bend outcomes to his will. Early indications suggest he has created significant doubt about the 2020 election: According to a recent NBC-Wall Street Journal poll, about 45 percent of voters do not believe that the election results can be counted accurately — a jump from 36 percent ahead of the 2016 election.
“When you’re wielding a conspiracy theory you can’t be proven wrong. The evidence doesn’t count against you,” said Jennifer Mercieca, a historian of American political rhetoric, a professor at Texas A&M University and the author of “Demagogue for President: The Rhetorical Genius of Donald Trump.”
Jennifer Palmieri, the communications director for Hillary Clinton’s 2016 presidential campaign, said she learned the hard way about fighting Mr. Trump’s disinformation. “It is extraordinarily hard to combat,” she said, adding that it became clear to her that he was willing to say and do anything when in 2015 he mocked Senator John McCain’s status as a war hero and paid no price.
Asked about Mr. Trump’s behavior over decades, Judd Deere, a White House spokesman, did not respond directly. “The American people know they never have to wonder what the president is thinking or how he feels about a particular topic, which is one of the many reasons why they chose to elect him over the same old recycled politicians who just use the poll-tested talking points,’’ Mr. Deere said.
Mr. Trump’s approach has been remarkably consistent, and often successful, as he has lied and spread falsehoods on matters big and small over the years. And he has found his biggest audience for it in the past five years.
“Americans have had a paranoid streak throughout their history, which this guy understands better than anybody,” said Hank Sheinkopf, a Democratic political strategist who watched Mr. Trump over decades in New York City. “If Joe McCarthy was alive, he’d say, ‘Well done.’”
When Mr. Trump was trying to get a tax abatement in 1982 to build Trump Tower on Fifth Avenue, the New York City housing commissioner at the time, Anthony B. Gliedman, received a mysterious call from someone who harassed him because the abatement had been denied.
The next day, Mr. Trump called the F.B.I. and said that he, too, had received a call from someone claiming to have read in the newspapers about the tax abatement being held up, according to F.B.I. records obtained by BuzzFeed. Mr. Trump claimed in the call, according to the F.B.I. records, that the caller mentioned someone else who had been “shafted” by Mr. Gliedman and that the caller planned to retaliate.
Mr. Trump, who has alternately derided and worked with the F.B.I. since his earliest days as a developer in New York — where organized crime had deep ties to the construction industries — told the F.B.I. officials he was reaching out to them in fear for Mr. Gliedman’s safety.
The caller was never identified. Years later, people familiar with the events said that some of Mr. Gliedman’s associates suspected that Mr. Trump was responsible for the menacing call to Mr. Gliedman.
Although the president has largely gotten away with his tactics, he at one point paid a hefty price for his campaign against Native American casinos. In 2000, Mr. Trump and some of his associates — including Roger J. Stone Jr., his oldest political adviser — paid the largest fine in the state’s history in a settlement for not disclosing that Mr. Trump had secretly paid for newspaper ads opposing a Native American casino north of New York City. Mr. Trump and Mr. Stone made no admission of wrongdoing in the settlement, and Mr. Stone has said the information in the ads was based in fact.
David Grandeau, the former head of the New York Temporary State Commission on Lobbying, recalled that Mr. Trump “didn’t want to go under oath,” and so he quickly admitted to what he had done when facing pressure.
By early 2011, Mr. Trump had moved on to a big political target: Mr. Obama, who Mr. Trump felt had not been effectively attacked by Mr. McCain, the 2008 Republican presidential nominee.
The idea to question the country of Mr. Obama’s birth, a conspiracy theory originally relegated to the fringes of the party, soon became central to Mr. Trump’s brief pseudo-campaign in 2011. The tactic drew in a segment of voters who did not like Mr. Obama and were open to a politician who would operate outside of good-faith practices. Mr. Trump soon shot up in the early primary race polls.
The “birther” efforts became a prototype. On a plane trip to Iowa in 2013, Mr. Trump asked Sam Nunberg, a former Trump aide and 2016 campaign adviser, whether he should question the citizenship of Senator Ted Cruz, Republican of Texas and a child of an American mother and a Cuban-born father who had moved to the United States from Canada when he was 4. Mr. Nunberg recalled that he advised that Mr. Trump support Mr. Cruz, a suggestion that Mr. Trump turned down.
“Trump said, ‘It’s not my job to defend him,’” Mr. Nunberg recalled.
By January 2016, as Mr. Cruz seemed poised to perform well in the Iowa caucuses, Mr. Trump was floating the idea that the senator could be tied up in court over challenges to his eligibility to serve. After Mr. Cruz won the caucuses, Mr. Trump dropped the tactic but went on to stoke unfounded and outlandish questions about whether Mr. Cruz’s father had played a role in the assassination of President John F. Kennedy.
“The genius in Donald Trump is that he knows how to control the conversation,” Mr. Nunberg said.
To that end, Mr. Trump often changes how he talks about people or things, depending on his own circumstances. A few years after his 1993 testimony about Native American gaming, he saw a financial advantage in an alliance with Seminoles and tried — ultimately unsuccessfully — to partner with them for casinos in Florida.
One of Mr. Trump’s favorite methods for casting doubt is to intone darkly that “there’s something going on” — a phrase he recently deployed in another attempt to question the mental acuity of Mr. Biden.
The president’s other technique is to say that he “hears something,” although he rarely says from whom, or that “many people” are saying something is the case.
“I heard it today that she doesn’t meet the requirements,” Mr. Trump said as he questioned the eligibility of Senator Kamala Harris, the Democratic vice-presidential nominee and the daughter of immigrants, to serve. It was an outright falsehood: Ms. Harris, who was born in California, is eligible for the office.
Mr. Trump used a similar formulation when he embraced a small but growing segment of the Republican base by praising proponents of QAnon, a wide-ranging online conspiracy movement that has claimed that the president is on a crusade to rid the world of satanic pedophiles organized by the Democratic Party and Hollywood celebrities.
“I’ve heard these are people that love our country,” Mr. Trump said last week during a White House news conference, speaking of QAnon followers. “So I don’t know really anything about it other than they do supposedly like me.”
George Arzt, a New York political consultant and former press secretary to Mayor Edward I. Koch who was once threatened with a lawsuit by Mr. Trump in a development dispute, said that sowing distrust has long served the president’s No. 1 goal.
“He was a person who was not interested in anything beyond winning,” in whatever way he could claim victory, Mr. Arzt said.