With his proposal to ban Muslims from entering the United States this week, Donald Trump added yet another tick to a growing list of negative and often outrageous rhetoric that has come to define his campaign.
Among other examples, he has repeatedly called his political opponents and others "stupid," "morons," "dummies" and "losers." He has attacked journalists, foreign leaders and ordinary citizens.
It's an unusual and in many ways, unprecedented strategy, experts say. But for a variety of reasons that analysts are still trying to pick apart, the negative approach seems to be working for Trump. In the last few months, he has developed a devoted base of supporters.
Photos: Shelter 'Trumps' Adoptable Animals
"The way people respond to negativity in politics is usually to disengage. And if they do engage, it's to think less of both the target and the person who did the attack," said Jennifer Mercieca, a historian of American political discourse at Texas A&M University in College Station.
"That's one reason pundits are having such a hard time understanding what's going on," she said. "Trump's campaigning does not make sense with any models that experts use for understanding political behavior."
Presidential candidates tend to take one of several standard approaches. Incumbents generally run positive campaigns and disregard everyone else who is running, Mercieca says. Meanwhile, challengers from the incumbent's opposing party often adopt a platform of reform or change, much like Obama did for the 2008 election.
Strangest Presidential Candidates in History
Trump is taking a different approach. Instead of rallying hope, like Obama did, he is playing off of people's fears, says Matt Motyl, a political psychologist at the University of Illinois at Chicago. And instead of trying to persuade undecided voters, like some candidates do, he is firing up a core base within his own party.
As puzzling as Trump's extreme language might seem, his oversized personality combined with recent news events likely help explain why he is managing to thrive on negativity, Motyl says. Studies show that when people are feeling fearful, they are more likely to gravitate towards charismatic candidates. In times of anxiety, people also seek out simple solutions instead of detailed plans.
10 Things You Can't Do and Become President
Trump tends to dwell on terrorism and other scary events. Then, with great confidence, he offers himself as the answer.
"He's always talking about threatening images and threatening forces operating behind the scenes or overseas or south of the border," Motyl said. "By fostering a sense of perceived threat, people become fearful. They want someone who can alleviate that fear."
Although Trump's speeches are full of disparaging comments about others, Mercieca suspects that it's not the negativity that's winning him fans. Instead, it's the distinction he draws between himself as good and everyone else as bad.
Unpresidential Moments in Presidential History
The same strategy has demonstrated success for political campaign ads, she says. Studies show that purely negative messages tend to backfire. But ads are more successful when they contrast the positive attributes of a candidate with the negative attributes of the opposition.
Trump doesn't run ads, but he does something similar with his rhetoric, says Mercieca, who recently watched several of his stump speeches with a close ear on the language he used.
"One of the things I found so fascinating was that so much of what he said was...'I'm winning. I'm the winner. I had the number one TV show. I had the number one book. I'm winning. I'm winning. I won. I'm great. They're dummies. They're dumb. They're stupid. They're vicious. They're dumb,'" she said. "He divides the world that way."
Trump's celebrity also makes him a unique case. At this stage in the race, with voting still many months away, most candidates are trying to build name recognition and introduce themselves to the public. But Trump has been on the scene for a long time, and people get the sense they already know him.
Emboldened by that familiarity, Merciera says, he repeatedly speaks off the cuff in a disorganized but repetitive way, while engaging in rhetoric of intimidation and war. She has also been struck by Trump's depiction of himself as a leader outside the control of the media, the Republican Party, political correctness or anything else.
"It's not a strategy we're familiar with," she said. "It's completely bizarre. And it's working."