U.S. political surveys show the two presidential front-runners, Republican Donald Trump and Democrat Hillary Clinton, are poised to move closer Tuesday to winning their parties' presidential nominations as voters head to the polls for nominating contests in five more states.

Two new polls Monday showed Trump, a billionaire real estate mogul who has never held elective office, with a commanding lead in the battleground southeastern state of Florida. He easily tops his nearest challenger there, Florida Senator Marco Rubio, and holds even bigger leads over Texas Senator Ted Cruz and Ohio Governor John Kasich.

One poll, by Quinnipiac University, showed Republican voters favoring Trump by a 46-to-22 percent margin over Rubio, while a Monmouth University poll pegged Trump's lead at 44 to 27 percent. Florida's winner-take-all primary is the biggest prize in Tuesday's Republican voting, with the victor collecting 99 delegates to the party's national nominating convention in July.

Delegate count
Delegate count

Narrow leads

Polls show Trump with smaller leads in North Carolina, Missouri and Illinois, with Cruz his closest competitor in these states, where national convention delegates will be apportioned according to the vote counts.

Trump, a one-time television reality show host, is locked in a close race in another winner-take-all contest with Kasich in Ohio, the Midwestern state he governs.  

Trump boasted at one rally Sunday, "If we can win Ohio, we're going to run the table, folks."

The party's losing 2012 presidential candidate, Mitt Romney, joined Kasich at campaign stops in Ohio in an effort to keep Trump from winning the 66 convention delegates at stake in the state.

Clinton, the country's secretary of state from 2009 to 2013, campaigned in the midwestern state of Illinois. She told cheering voters in Chicago, "I'm going to fight for working people. I'm going to fight for good jobs."

Delegates at stake on Tuesday, March 15
Delegates at stake on Tuesday, March 15

Clinton's major leads

Clinton has a commanding lead in the race to secure the Democratic presidential nomination over her lone challenger, Vermont Senator Bernie Sanders, a democratic socialist who has focused his campaign on growing income inequality and the clout of Wall Street financial chieftains.

Polling shows Clinton with big leads among Democratic voters over Sanders in Florida and North Carolina, with closer contests possible in Illinois, Ohio and Missouri. None of Tuesday's Democratic contests are winner-take-all.

Tuesday's voting is coming after days of acrimony at Trump campaign stops, where some of his supporters and those opposed to his candidacy have engaged in heated name-calling, pushing, shoving and an occasional hand-to-hand fight.

Trump at times has called for his supporters to physically engage demonstrators and regularly tells security officials to "get them out" when protesters shout at him when he is speaking. But he said he wants peace, not trouble at his campaign events.

Trump's political foes have blamed his rhetoric for the confrontations, while he claims the Sanders campaign has dispatched supporters to Trump's rallies to disrupt them.

Sanders has denied that contention and called Trump a "pathological liar. Clinton has called Trump a "political arsonist."