U.S. presidential candidates disagree about who is responsible for violence at recent political rallies.

Republican candidate Donald Trump said he is not responsible for violence at his rallies. But in recent weeks, fighting and conflict has erupted in rallies in Missouri, North Carolina, Ohio and Illinois. In Chicago, a Trump rally was cancelled.

Trump blamed Democratic candidate Bernie Sanders for the fighting. Sanders said his supporters had disrupted Trump events. But he denied ordering his campaign followers to disrupt Trump events.

"We want peace. ... We don't want trouble," Trump said at an Illinois rally Sunday. Trump then said he may send his supporters to Sanders rallies.

Sanders responded by inviting Trump supporters to any upcoming rally.

"Send them," Sanders said. "They deserve to see what a real honest politician sounds like."

Violence has increased at these political events. In Ohio on Saturday, a protester rushed the stage while Trump was speaking. Secret Service agents stopped the man.

In North Carolina, a Trump supporter assaulted a protester as security guards escorted the protester out of the event.

The Trump protester was charged with assault.

Primary elections will happen in Florida, Illinois, Missouri, North Carolina and Ohio on Tuesday.

I'm Dorothy Gundy.

VOANews reported on this story. Jim Dresbach adapted the report for Learning English. Kathleen Struck was the editor.