Washington: US Presidential election 2016 is on the boil as Hillary Clinton and Bernie Sanders both attacked Donald Trump on Sunday, accusing the Republican frontrunner of inciting violence.

Clinton launched a vehement attack on Trump calling him "bigoted" and alleging he had perpetrated "political arson." The Vermont senator claimed that Trump is a "pathological liar".

"It is clear that Donald Trump is running a very cynical campaign pitting groups of Americans against one another. He is trafficking in hate and fear," Cinton said during the event at Ohio State University. "He actually incites violence in the way he urges his audience on, talking about punching people, offering to pay legal bills."

Clinton said that the billionaire businessman was guilty of a case of "political arson" as he was throwing fuel on political divisions in the country. "He has been incredibly bigoted towards so many groups," she continued. "You don't make America great by tearing down everything that made America great."

The former secretary of state followed Sanders at the town hall moderated by CNN's Jake Tapper and TV One's Roland Martin. Both Sanders and Clinton - Democratic presidential hopefuls - are making closing arguments to voters in their increasingly contentious Democratic nominating marathon. The two leaders made the arguments just two days before five states vote in crucial primaries.

"I hesitate to say this because I really don't like to disparage public officials, but Donald Trump is a pathological liar," Sanders said.

Sanders also targeted Trump for saying that he was willing to pay the legal fees of a man charged with punching a protester at one of his rallies. "I would hope Mr. Trump tones it down big time and tells his supporters that violence is not acceptable in the American political process," Sanders said.