Facing bipartisan condemnation for a campaign rally that ended in violence, an unrepentant Donald Trump on Saturday blamed the near-riot on opponents who he said harassed his supporters and trampled on his freedom to speak.

Citing the protests Friday night in Chicago, two of his Republican rivals hedged on promises to back the front-runner if he emerges as the GOP nominee.

Democrats seized on the incident to again question Trump's honesty and fitness to serve as president.

Engulfed in controversy — as he has been repeatedly since launching his White House bid — Trump was defiant. He even suggested the upheaval, which played on cable television for hours Friday night and Saturday, would help his candidacy.

"Yesterday in Chicago, we had a little bit of a problem," Trump told boisterous supporters at a Cleveland rally, his second Ohio stop of the day as he campaigned ahead of the state's crucial primary on Tuesday. "We were not allowed to exercise our 1st Amendment rights.

"It just makes all of our friends and supporters more angry," he continued, "and we're going to go to the polls on Tuesday, and it'll be a resounding victory."

The crowd roared, as they did several times when small groups of protesters tried to interrupt the Manhattan businessman and reality TV star in what has become a regular occurrence at his campaign events.

Activists angered by Trump's inflammatory statements on immigration, Islam and other topics now show up at nearly all of his public events. At a Kansas City, Mo., rally Saturday night, where Trump was heckled through most of his remarks and police pepper-sprayed demonstrators outside, he threatened to start having them all arrested.

"They'll have to explain to Mom and Dad why they have a police record and why they can't get a job," Trump said.

Tensions ran high at all three of Trump's Saturday events.

At his morning rally here outside Dayton, a man jumped a barricade and ran toward Trump. Secret Service agents leaped on stage and surrounded the candidate as colleagues tackled the man. A flustered Trump quickly collected himself and resumed his remarks.

Protesters clash with Donald Trump supporters at a rally for the Republican presidential front-runner.

Trump later alleged the man was tied to the Islamic State terrorist group, but there was no evidence to support the charge.

The rally Friday night at a Chicago sports arena was a spectacle of mayhem. A large, angry demonstration before the candidate arrived led him to abruptly cancel his appearance. Fights between agitated Trump supporters and protesters spilled into the streets and resulted in injuries and arrests.

The clashes marked the most violent episode of a campaign that has grown increasingly combative, in good part because of the inflammatory rhetoric of Trump and its effect on some of his more militant supporters.

Ohio Gov. John Kasich, campaigning three days before the must-win primary in his home state, accused his rival of poisoning the country's politics.

"There is no place for a national leader to prey on the fears of people," Kasich told reporters outside Cincinnati. Asked if he could still back Trump as the GOP nominee — as he and others promised in a debate earlier this month — Kasich replied, "It makes it extremely difficult."

Pressed further, he added, "Take a deep breath and see where it goes."

Sen. Marco Rubio of Florida, who also faces a must-win primary in his home state on Tuesday, was blunter still.

"This boiling point that we have now reached has been fed largely by the fact that we have a front-runner in my party who has fed into language that basically justifies physically assaulting people who disagree with you," he told reporters in Largo, Fla.

Asked whether he would back Trump as the party's nominee, Rubio responded, "It's getting harder every day."

Sen. Ted Cruz of Texas, the rival running closest to Trump in both delegates and states won, joined in the criticism, but said at a Missouri campaign stop: "I understand people who are supporting Donald Trump. They look at him — he is a loud, angry, profane and cursing voice, and that feels like a vessel for that anger."

Unlike the others, Cruz reiterated his pledge to back Trump if he becomes the party's choice to face the Democratic ticket in the fall.

It is far from clear whether the violence in Chicago will loosen Trump's hold on his millions of supporters. He has survived numerous scrapes that would have doomed other politicians, and often ended up stronger as a result.

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Hopscotching between states on his private jet, Trump said at the airport rally outside Dayton that the problems arose when "all of a sudden a planned attack just came out of nowhere."

"My people are nice … they caused no problem," he said. "They were taunted; they were harassed by these other people."

Trump said the protests were the work of professional agitators, many associated with Bernie Sanders, the Democratic presidential hopeful. "Frankly, it would have been easier to go, but I didn't want to see anybody get hurt," Trump said. He later said people could have been killed.

Sanders responded by calling Trump "a pathological liar."

"What caused the protests at Trump's rally is a candidate that has promoted hatred and division against Latinos, Muslims, women and people with disabilities, and his 'birther' attacks against the legitimacy of President Obama," Sanders said.