Observers have been worrying about heightened tensions at Donald Trump rallies for while, and now they're turning violent.

On Wednesday night, a Trump supporter sucker-punched an African-American protester as he was being escorted out of a rally in Fayetteville, North Carolina.

Last month, a Secret Service agent choke-slammed a Time Magazine photographer after he left the media pen to photograph a group of protesters.

And at Trump press conference on Tuesday night, a Breitbart News reporter was reportedly yanked by the arm by Trump's campaign manager (though the campaign disputes that account).

Such violence, which is unprecedented in the history of modern presidential campaigns, is the inevitable result of the charged anti-protester and anti-media rhetoric coming out of the mouth of the candidate himself, reporters and observers say.

Nearly every day for the last three months, Trump has stood before crowds of thousands and encouraged his fans to heckle protesters and reporters.

In February, as a protester was being escorted out of a rally in Las Vegas, Trump said: "I'd like to punch him in the face."

"I love the old days," Trump said. "You know what they used to do to guys like that when they were in a place like this? They'd be carried out on a stretcher, folks."

At another rally, Trump told his supporters "knock the crap out of" protesters if they threw tomatoes at him. "I will pay for the legal fees. I promise," he said.

Since December, Trump has referred to the media as "absolute scum" and "the most dishonest people," while encouraging his audience to boo the reporters who are gathered in fenced-off press pens that they are not allowed to leave.

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Several reporters say they have heard supporters shout "go to hell," and at least one female reporter recalls being referred to as a "bitch."

But in recent weeks, the anger and vitriol from Trump and his supporters have created fraught environments where physical altercations seem likely to explode at any moment.

Weeks after Trump said he wanted to punch a protester in the face, John McGraw, a 78-year-old supporter, actually did so. The Fayetteville police have brought charges against McGraw, according to Fayetteville station WRAL.

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The seeds of the current situation have been sewn over months, both on stage and off.

In November, when CNN reporter Noah Gray left the press pen to report on an incident in the crowd, Lewandowski threatened to have him blacklisted from all future Trump rallies.

"Inside the pen, or I will pull your credentials," Lewandowski told Gray. He also told his colleague Hope Hicks, Trump's spokesperson, to tell Gray "to get back in the pen or he's f***ing blacklisted."

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While reporters covering Trump are reticent to discuss the campaign's tactics on the record, outside observers are becoming more and more vocal about what they see as a dangerous trend.

"Whether Trump gets the nomination at the convention or is denied it," Politico's Edward-Isaac Dovere tweeted on Thursday, "there seems about 100% chance of violence