Ahead of key elections dubbed Super Tuesday II, presidential hopefuls from both parties have turned up the heat on businessman Donald Trump for what they see as his pivotal role in campaign violence.
Mr Trump has come under nearly non-stop fire from his rivals since last Friday, when violence erupted at his planned rally in Chicago. On Sunday, they hit him with some of their strongest words yet.
Speaking at a Democratic Party town hall organised by CNN, former secretary of state Hillary Clinton repeated her characterisation of Mr Trump as a political arsonist and rebuffed his claims that he was not responsible for last week's ugly scenes.
"You know, he has lit the fire, and then he throws his hands up and claims that he shouldn't be held responsible, and he should be held responsible," she said.
At the same town hall, Senator Bernie Sanders, in turn, called Mr Trump a "pathological liar" when asked to respond to allegations that he had asked supporters to disrupt Trump events.
He also hammered the billionaire for considering to pay legal fees of a supporter who sucker-punched a protester.
"What that means is that Donald Trump is literally inciting violence with his supporters. He is saying that if you go out and beat somebody up, that is OK, 'I'll pay the legal fees'. That is an outrage and I would hope that Mr Trump tones it down big time."
Mr Trump's Republican rivals also sharpened their criticisms in the countdown to the winner-takes-all contests in Ohio and Florida today.
On Sunday, Mr Trump's main rival in Florida, Senator Marco Rubio, said in an interview that the Republican front runner had turned "the most important election in a generation into a circus, a complete fiasco".
Ohio Governor John Kasich, who is in a close race in his home state with Mr Trump, said that the political atmosphere has become toxic.
"The environment is there and he needs to back off of this," he said on a Sunday morning news show.
Senator Ted Cruz called for a president who can unite the country. "We've seen a president dividing us for seven years. We don't want to see that going forward."
Mr Trump sounded a defiant note - even as his campaign rolled out new security measures. He told a crowd of about 10,000 in Boca Raton on Sunday evening that he had to call off his Chicago event to protect his supporters. "We want safety, we want happiness, we want everyone to go home really happy, really peaceful," he said.
Campaign staffers confiscated homemade signs in Boca Roca, whether for or against the candidate. The campaign, instead, handed out printed signs.
Ms Kate Newton, 52, a writer who had showed up to protest with a "Stop the hate" sign, was asked to leave after she refused to hand it over.
"There's just too much hate spread by Trump and his supporters. I'm here to carry out a peaceful protest," she told The Straits Times.
Attendees also had to give up their umbrellas and water bottles at the door.
The campaign made an announcement ahead of Mr Trump's speech, telling supporters not to "touch or harm" protesters. Instead, they suggested that people should chant "Trump" to notify police officers.
One heckler was surrounded by chanting supporters and police quickly escorted the lone protester out.
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