The Republican frontrunner in the race for US president, Donald Trump, was interrupted by protesters during campaign rallies in Ohio and Missouri one day after security concerns forced him to back out of an appearance in Chicago.
A man tried to storm the stage while the billionaire businessman addressed a rally in Vandalia, Ohio, according to media reports.
Broadcast video showed Secret Service agents immediately surrounding the candidate, and the protester was arrested and charged with disorderly conduct and inducing panic, according to local broadcaster WDTN.
Later in Cleveland, Ohio, security officers had to escort protesters who tried to disrupt Trump's speech out of an arena.
Trump taunted the protesters as the were shown the door, saying, "Hey look it's a Bernie person," referring to US Senator Bernie Sanders, one of his Democratic rivals.
When hecklers repeatedly tried to interrupt him at an evening rally in Kansas City, Missouri, Trump said "Get him out" over and over again, and at one point said "to hell with them".
The Sanders campaign said there was no evidence any of its staff was involved in organising the protests.
The incidents at Trump's campaign rallies on Saturday followed a volatile situation on Friday night in Chicago, where fighting broke out between anti-Trump protesters and supporters of the candidate, prompting Trump to cancel his appearance.
Trump critics say his own statements at campaign rallies have fanned the flames and helped escalate the situation to violence.
Democratic frontrunner Hillary Clinton called Trump's rhetoric "political arson".
She said Trump's "ugly, divisive rhetoric" is wrong and dangerous.
The other contenders in the presidential race also were out stumping on Saturday ahead of crucial votes on Tuesday in five states - Illinois, Missouri, Ohio, Florida and North Carolina.
If Trump's momentum continues, he will be in the best position of the four Republican candidates still in the race to capture the GOP nomination.
Voting took place on Saturday on two US territories, the Mariana Islands and Guam, the state of Wyoming and Washington, DC.
Clinton won the Marianas, which was contested only by Democrats, with 54 per cent, claiming her 14th victory overall.
US Senator Ted Cruz finished ahead in Guam and was leading in Wyoming with 68 per cent with about 91 per cent of the vote counted, according to the New York Times.
Results from Washington were expected later on Saturday.
Much of the attention on Tuesday will be on Ohio and Florida because they have the most delegates.
US Senator Marco Rubio, whose campaign has struggled to pick up momentum in recent weeks, campaigned in his home state of Florida.
In an interview with the New York Times he compared Trump to a "third-world dictator" and said he was "leading the country dangerously close to a boiling point".
Ohio Governor John Kasich, campaigning in Ohio, didn't mention Trump, but said there was no place in US politics for a national leader to "prey on the fear of the people".
