It was a question that most major presidential candidates would have quickly dismissed as absurd, even offensive: What do you make of these theories that Justice Antonin Scalia was murdered? For Donald J. Trump, it appeared unavoidably juicy, and possibly the next big pop-culture fixation. “You know, I just landed, and I’m hearing it’s a big topic,” Mr. Trump told the radio host Michael Savage from South Carolina, in an interview just a few days after the Supreme Court justice’s unexpected death.
Even as he said he could not speak to whether a special commission should investigate the death, he added, “They say they found a pillow on his face, which is a pretty unusual place to find a pillow.”
Mr. Trump, unlike most presidential candidates, does not shrink from addressing, and in some ways legitimizing, the wildest of hypotheticals. He has declared on a presidential debate stage that he knew a 2-year-old who immediately developed autism from a vaccination. He has appeared on the radio show of the noted conspiracy theorist Alex Jones, who has suggested that the government played a role in the Sept. 11, 2001, terrorist attacks and the 2013 Boston Marathon bombings. He has said on Twitter that President Obama might have attended Justice Scalia’s funeral had it been held at a mosque, feeding into the pervasive rumor that the Christian president is actually a Muslim. And he shared with a rally crowd a dramatic story of a United States general executing Muslim insurgents with bullets dipped in pigs’ blood, which has been dismissed as an Internet rumor.
Part hair-salon gossip, part purveyor of forwarded conspiracy emails, Mr. Trump has exploited the news cycles of an Internet era in which rumors explode like fireworks and often take a long time to burn out. Mr. Trump’s willingness to touch on what passes for fact on fringe websites puts him in a unique class for a national major party front-runner.
“It’s like a walking, talking Enquirer magazine,” said Erick Erickson, the former editor in chief of the conservative website RedState, referring to the popular supermarket tabloid National Enquirer. Mr. Erickson often shut down interest in conspiracy theories on his website, such as the so-called birther rumors that Mr. Obama was born in Kenya.
Such supermarket tabloids “do very well — people do like the stories of aliens meeting with presidents,” said Mr. Erickson, who has often clashed with Mr. Trump.
It is not a total surprise that Mr. Trump is the candidate most likely to use the phrase “I hear” before stating something as fact, no matter how flimsy the information he passes along. A man who reveled in his presence in the New York tabloid pages for decades, he saw firsthand the power of stories, especially those that shock people, to command attention. But the expectations for what a presidential standard-bearer would pass along have typically been higher.
It was the “birther” theories that Mr. Trump used to stoke interest in his own potential candidacy in 2011. That year, he repeatedly demanded that Mr. Obama produce his Hawaiian birth certificate. In April of that year, he claimed to have sent investigators to the state: “They can’t believe what they’re finding,” he said, though he has never made public any such findings, and Mr. Obama later released his birth certificate.
Mr. Trump has since tried to steer clear of the birthplace claims about Mr. Obama. But he used similar questions to try to inject doubt about Senator Ted Cruz of Texas, who was born in Canada to a United States citizen.
The candidate has used Twitter to pass along other dubious theories, including false crime statistics about blacks and questions about Senator Marco Rubio’s eligibility to be president. Mr. Rubio was born in the United States.
Pressed about passing along such conjecture by the ABC News host George Stephanopoulos on Feb. 21, Mr. Trump gave a response he frequently uses to deflect responsibility for sharing inaccurate information. “Somebody said he’s not, and I retweeted it,” Mr. Trump said. “We start a dialogue, and it’s very interesting.”
Mr. Trump’s campaign manager, Corey Lewandowski, said his candidate was not bound by convention and looked to start conversations, not to be a mediator of topics. “The great part about the Internet is, it gives a forum for people to express their ideas, and when he sees an idea that he thinks is worthy of having a discussion about,” Mr. Lewandowski said, Mr. Trump will sometimes repost things that he does not agree with.
As for what he says, Mr. Lewandowski said, “Mr. Trump is willing to have conversations and discuss issues that other candidates aren’t willing to discuss because they’re so politically correct.”
But some of the subjects Mr. Trump has flirted with during his candidacy are darker, and more consequential, such as the mosque post about Mr. Obama and Justice Scalia’s funeral, which he later insisted was meant to be a joke.
He has also promoted the notion that vaccines cause autism, a claim that has been widely debunked by doctors and scientists. “Just the other day, 2 years old, 2-and-a-half-years old, a child, a beautiful child went to have the vaccine, and came back, and a week later got a tremendous fever, got very, very sick, now is autistic,” Mr. Trump said at a Republican debate in September.
When another presidential candidate, Michele Bachmann, then a Minnesota congresswoman, made a similar claim in the 2012 campaign, she was savaged by news media commentators for the remarks; Mr. Trump received little serious blowback.
And an Internet rumor around the time of the Sept. 11 attacks about Muslims in New Jersey cheering the fall of the World Trade Center towers was cited as fact by Mr. Trump, who said that “thousands” of Muslims had hailed the attacks, spurring weeks of controversy in the fall. To buttress his case, he reposted information on Twitter from the website Infowars, hosted by Mr. Jones, the conspiracy theorist.
More recently, at a South Carolina campaign event, Mr. Trump touched on the smoky theory that the identity of those who funded the attacks was still not publicly known. If he wins, he said, “you will find out who really knocked down the World Trade Center.”
Christopher Ruddy, the editor in chief of the conservative website Newsmax, said Mr. Trump’s popularity was driven in part by the larger mistrust of traditional institutions, including the mainstream news media.
“I’m not so sure he believes there’s anything to these things, but I believe he enjoys the conversation about it; it keeps the script moving,” said Mr. Ruddy, who wrote a book on the death of the former Clinton White House aide Vincent W. Foster Jr., which was ruled a suicide but remains a topic of conspiracy theories.
Mr. Trump, Mr. Ruddy said, is using a stream-of-consciousness style, speaking “as if you were the neighbor next door or a friend of his.” That “we’re just chatting” approach has let working-class voters see the New York plutocrat as someone to whom they can relate, Mr. Ruddy said.
And by virtue of his newness as a phenomenon, he is able to withstand what could otherwise be withering scrutiny. “It works for him, where it wouldn’t work for other people,” Mr. Ruddy said.
But to publicly entertain such theories, Mr. Erickson said, means sliding down a dangerous slope. “You hand yourself over the idea that there’s an invisible hand at work that you can’t see,” he said. “You then begin to cast about to blame someone for controlling that invisible hand, and you lose perspective on what is and is not happening, and what is and isn’t real.”
The primary season has shown that there is little downside for candidates who stretch the truth. Whether Mr. Trump changes his approach if he becomes the party’s nominee and faces millions of independent and Democratic voters remains to be seen. But for now, Mr. Trump has embraced the funhouse-mirror aspect of his party’s fringe.
One of his notable media stops at the end of 2015 was a half-hour visit with Mr. Jones, on his wide-reaching radio show. Mr. Jones ended the program by thanking his guest, adding, “You will be attacked for coming on, and we know you know that.”