Tuesday looms as a major day in the U.S. presidential race, as voters in five large states head to the polls for primaries that could go a long way toward determining the presidential nominees for both political parties.

The primaries in Florida, Illinois, Missouri, North Carolina and Ohio. Voting is taking place amid a backdrop of protests and some violence at rallies for the Republican front-runner, billionaire real estate mogul Donald Trump.

Trump cancelled a rally Friday night in Chicago after clashes between protesters and supporters. Several other Trump rallies have been interrupted numerous times by demonstrators, and on Saturday Trump was quickly surrounded by U.S. Secret Service agents after a man leapt from the crowd and dashed toward the stage, only to be tackled by security and led away.

Trump later told another rally in Missouri he was ready to defend himself had the protester made his way on stage. “I don’t know if I would have done well, but I would have been boom, boom, boom,” he said, pounding his right fist into his left hand.

What to Watch for in Tuesday's US Presidential Primaries

Pablo Ramos, of Orlando, holds a campaign sign as
Pablo Ramos, of Orlando, holds a campaign sign as he waits for Republican presidential candidate Donald Trump to speak prior to a campaign event in Tampa, Fla., March 14, 2016.

Trump leads in Florida; Ohio race tight

Despite the chaos at recent Trump rallies, the Republican front-runner is positioned to do well in the five states voting on Tuesday. Three new polls (NBC News-Wall Street Journal-Marist/Quinnipiac University/Monmouth University) give Trump a double-digit lead in Florida over home state Senator Marco Rubio. A Rubio loss in Florida likely would lead to calls from other Republicans that he abandon his White House ambitions.

Trump expressed confidence during a rally in Florida. “We have a movement going on, folks, this isn’t just us here. This is all over the country. The same thing is happening!”

On Friday, Trump was endorsed by former rival Ben Carson. Trump used the occasion to urge the Republican Party establishment to acknowledge his success. “We have numbers, I guess it averages about 65 percent more, but that represents many millions of people.  And if the Republican so-called establishment is smart, they will embrace it because there is no way we can lose. There is no way we can lose.”

Police officers forcibly restrain a protester at U
Police officers forcibly restrain a protester at U.S. Republican presidential candidate Donald Trump's campaign rally in Fayetteville, North Carolina, March 9, 2016.

Concerns about Trump’s tone

But the chaotic scenes from his rallies in recent days have sparked condemnation not only from Democrats but from some of his Republican rivals as well. Rubio urged voters in Florida to spurn what he called the politics of hate. “Embrace leaders who do not ask you to give them your vote on fear and hopelessness, but instead to vote for them on the basis of how great our country can be if we do what needs to be done.”

Trump’s biggest challenge on Tuesday likely will come in Ohio, where he and Ohio Governor John Kasich are locked in a tight battle for the state’s 66 Republican delegates. Both Ohio and Florida are winner-take-all contests on the Republican side.

Kasich said he refuses to “take the low road” to the highest office in the land and has called out Trump for his divisive tone. “Donald Trump has created a toxic environment, and a toxic environment has allowed his supporters and those who sometimes seek confrontation to come together in violence.”

A Kasich victory in Ohio could slow Trump’s march to the Republican nomination and prevent the front-runner from securing the 1,237 delegates he needs to claim the nomination prior to the party's convention in Cleveland in July.

“It’s very difficult to see somebody getting 1,237 other than Trump,” said Henry Olsen of the Ethics and Public Policy Center in Washington. “So if Trump has a 70 percent chance of winning, it means he has a 30 percent chance of not, and I would say it is a 30 percent chance that you will have an open convention.”

Supporters cheer as Democratic presidential candid
Supporters cheer as Democratic presidential candidate, Sen. Bernie Sanders, I-Vt, speaks at a campaign rally at the Akron Civic Theatre, March 14, 2016, in Akron, Ohio.

Sanders looks for more upsets

Democrats Hillary Clinton and Bernie Sanders also will be competing for delegates on Tuesday. Clinton has a big lead in Florida but Sanders is looking to close the gap in Illinois and Ohio, hoping to build off his upset last week when he narrowly beat Clinton in Michigan.

Clinton would like to shift her attention to the Republicans, but knows the Democratic race could drag on for weeks unless she can score a string of victories over Sanders. Clinton told supporters in Tampa, Florida she is ready no matter whom the Republicans nominate in July. “You know, people ask me all the time, who do I want to run against? That is not for me to decide.  But given what they have all said, I will take any one of them.”

Sanders continues to draw large and enthusiastic crowds to his events, including a recent rally near the University of Florida at Gainesville. “The reason we are doing so well and the reason there is so much momentum for this campaign is that we are doing something pretty radical in American politics.  We are telling the truth!”

There are no winner-take-all contests on the Democratic side. Delegates are awarded on a proportional basis for all the caucuses and primaries, and that could extend the race all the way into early June.

WATCH: Florida voters discuss candidates