Donald Trump has threatened to send his supporters to disrupt Bernie Sanders' campaign events.
Trump said "fervent" supporters of Sanders were to blame for the violence that caused his campaign event in Chicago to be canceled Friday evening due to security concerns.
But Sanders denied he had sent protesters to Trump's rally. "As is the case virtually every day, Donald Trump is showing the American people that he is a pathological liar," Sanders said. "Obviously, while I appreciate that we had supporters at Trump's rally in Chicago, our campaign did not organize the protests."
Trump tweeted Sunday that Sanders was lying when he said he had not ordered his supporters to protest at his events and warned him to "be careful."
Trump's rally was scheduled to take place at the University of Illinois at Chicago Pavilion, but protests and scuffles both inside and outside the arena caused the event to be called off at the last minute, leaving sullen Trump supporters to file out to the cheers of protesters.
Speaking to supporters at a rally in Dayton, Ohio, Saturday, the Republican frontrunner criticized what he said was the "disgraceful" behavior of anti-Trump protesters. He called the demonstrations "a planned attack" carried out by "organized, professionally staged wise guys."
"What happened yesterday was incredible," Trump said. "It was determined that if we go in it could cause really bad, bad vibes."
"You have to understand they want me to tell my people, ‘Please be nice.’ My people are nice!" he said to cheers. "They caused no problems. They were taunted, they were harassed by these other people."
Trump said some of the protesters represented "our communist friend" Bernie Sanders.
"Bernie, he should really get up and say to his people, 'Stop!'" Trump said.
The real-estate developer said there were no Hillary Clinton supporters at the rally because they lack the "fervor" of Sanders supporters. "Say what you want about Bernie, at least there’s fervor," he said.
In the aftermath of the Chicago event, Trump's opponents for the Republican nomination have also said he is ultimately responsible for the actions of his supporters due to his often incendiary rhetoric.
"I think a campaign bears responsibility for creating an environment, when the candidate urges supporters to engage in physical violence to punch people in the face,” Ted Cruz said. “The predictable consequence of that is that it escalates."
Speaking Saturday, Trump mocked his rivals for saying such behavior would not occur at their rallies. "They don't have any people at their rallies!" he said.