Trump, Other White House Hopefuls Face Huge Test Tuesday

Dubbed "Super Tuesday 2" by US media, the latest major date in the run-up to November's election will see Democratic and Republican primary contests in the states of Florida, Illinois, Missouri, North Carolina and Ohio.

"I love you Ohio. You can make the difference!" Trump said at an evening rally at the Youngstown airport, as he suggested the Midwestern state, widely seen as a microcosm of America, was his closest race of the five where delegates are up for grabs Tuesday.

Violent clashes and protests at Trump rallies over the weekend dominated US headlines, with rivals in both parties accusing the billionaire real estate mogul of creating a toxic campaign environment.

The latest polls showed the Republican frontrunner poised to win the Tuesday contests, although Ohio's Governor John Kasich held a narrow lead in his state in some surveys, AFP reported.

A Kasich victory in Ohio may be the last chance to derail Trump's march to July's Republican nomination, especially as Tuesday marks the point when the party moves to a winner-takes-all format in terms of the delegates accorded for each primary win.

Trump struck a blue-collar tone as he urged Ohio to reject their popular governor, saying he was better positioned to re-invigorate the state's struggling economy.

"Your steel industry is dead," Trump said. "I'm going to bring your industry back."

Florida, Illinois and Ohio are the day's biggest prizes for both parties, as each state offers large delegate hauls.

Among Democrats, frontrunner Hillary Clinton is poised to extend her lead over rival Bernie Sanders, if polls prove accurate.

She is handily ahead in Florida, but in Ohio the former secretary of state only held a five-point lead, according to a Quinnipiac University poll out Monday.

Sanders, appealing to blue-collar voters, has made impressive gains in the state, after trailing by as much as 30 points in polls last month.