A defiant Donald Trump touched off a political maelstrom Sunday that didn’t spare his Republican and Democratic presidential rivals, as he threatened to encourage supporters to stage protests against Sen. Bernie Sanders and drew escalating criticism from GOP opponents desperate to slow him ahead of Tuesday’s crucial nominating contests.

The mogul’s impact on both political parties illustrated the unusual position he occupies in the race. His unpredictable and combative approach will face its biggest test yet this week in five primaries that offer him an opportunity to effectively put away his Republican competition.

A new round of public polling showed Trump leading comfortably in Florida, Tuesday’s biggest prize.

In Ohio, another delegate-rich state that is seen by many Trump critics as perhaps the last best chance to force the front-runner into a lengthy battle for the nomination, surveys showed he was in a close fight with the state’s governor, John Kasich. Trump scrapped plans for a ­Monday-evening rally in Florida and replaced it with one in Ohio.

The other primaries Tuesday are in Illinois, Missouri and North Carolina.

There will also be Republican caucuses in the Northern Marianas.

Here in Florida, Sen. Marco Rubio made a last-minute push to avoid a humiliating loss in his home state that supporters fear would end his campaign. Sen. Ted Cruz of Texas campaigned in North Carolina and Ohio, attempting to position himself to add to his delegate total, which is second only to Trump’s. Kasich, who has yet to win a state, made an urgent push on his home turf.

On the Democratic side, front-runner Hillary Clinton tried to put more distance between herself and Sanders, who won an upset victory in Michigan last week.

Throughout it all, the presence of Trump — who has come under heavy criticism from opponents who have bluntly accused him of fueling divisive discourse and violent clashes at his events — could be felt.

The billionaire businessman did not bow to calls to soften his aggressive tone. Instead, he lashed out at his Republican competition and blamed San­ders’s supporters for forcing him to cancel a rally set for Friday in Chicago, where violence spilled onto the streets.

“Bernie Sanders is lying when he says his disrupters aren’t told to go to my events,” Trump said on Twitter.

Republican presidential candidate Donald Trump speaks during a campaign event at the Savannah Center in West Chester, Ohio on Sunday. (Jabin Botsford/The Washington Post)

“Be careful Bernie, or my supporters will go to yours!”

In a campaign stop in Bloomington, Ill., Trump said there would be a double standard if his backers disrupted rallies for the senator from Vermont.

“They’ll lock you up for the rest of your life and give you the electric chair and say, ‘Oh, poor Bernie, poor Bernie, he had to endure this!’ ” Trump said. “With us, they don’t say that.”

At his hour-long event, Trump also called Cruz a “liar” and said Kasich was weak on trade.

Further inflaming tensions, Trump said on NBC’s “Meet the Press” that he has instructed his staff to look into paying legal fees for a 78-year-old white man who has been charged with sucker-punching a 26-year-old black protester at one of the real estate magnate’s recent rallies.

Trump said in an interview on CNN’s “State of the Union” that he didn’t consider his “Be careful Bernie” social-media post to be a threat.

He repeated his charge that Sanders had lied when he said his campaign wasn’t behind an influx of protesters that led to the cancellation of the planned Chicago rally.

Appearing on the same program, Sanders said Trump was not being truthful.

“This man cannot stop lying,” Sanders said. He said that he has many supporters and that while some may attend Trump events as a form of peaceful protest, they are not doing so at his direction.

“I would hope my supporters will not disrupt meetings,” Sanders said. “We have millions of supporters, and people do things. But it was not our campaign.”

He blamed Trump for creating the environment that has led to violence at his rallies.

“This is a man who keeps implying violence, and then you end up getting what you see,” Sanders said.

Trump’s three GOP competitors issued sharp denunciations of their own.

“Do we really want to live in a country where Americans hate each other? Where people are incapable of talking through an issue?” Rubio asked a crowd gathered at a sprawling retiree community here in The Villages. Without naming Trump, Rubio said the country is seeing ­“images we have not seen since the 1960s.”

Campaigning in Strongsville, Ohio, Kasich said of Trump: “Well, look, I can’t control him. I’ve already said that what he’s done is create a toxic atmosphere. I just do what I can do.”

Speaking at an event put on by his super PAC in Concord, N.C., Cruz continued to argue that he is the only candidate who can beat Trump, urging people who support other candidates to throw their votes behind him to ensure Trump doesn’t get the nomination.

“Come join us, come on in, the water’s fine,” he said.

Surveys from NBC News, the Wall Street Journal and Marist College, as well as polling from CBS News and YouGov, showed Trump leading Rubio by double digits in Florida and Cruz threatening Rubio for second place. Rubio has campaigned before small crowds in recent days.

In Ohio, new polling showed Trump and Kasich in tight competition at the head of the pack. Ohio will award 66 delegates to the victor there. Florida will give all 99 delegates to its winner.

For the Democrats, the five contests that will be held Tuesday could be key to shaping the rest of the race.

Clinton leads in the delegate chase and is looking to pull away. Sanders is aiming to build on his come-from-behind victory in Michigan with strong showings in the Midwestern states of Missouri, Illinois and Ohio.

Clinton has held wide leads in polling in Florida, and Sanders is angling to keep it close in North Carolina.

A day after the former secretary of state lambasted Trump’s rhetoric as “political arson,” she focused her message for much of Sunday on jobs and trade as she campaigned in Ohio. But Sunday evening at a Democratic dinner in Columbus, she unleashed her most critical assessment of the real estate mogul yet, accusing him of doing anything to get votes.

“Donald Trump is running a cynical campaign of hate and fear, for one reason: to get votes,” she said. “He’s encouraging violence and chaos to get votes. He is pitting Americans against each other to get votes.”

In addition to his back-and-forth with Trump, Sanders took aim at Clinton during his rally in the St. Louis area, outlining what he said are “strong” differences on trade, accepting donations from Wall Street, and the Iraq War.

Sanders’s advisers argue that after Tuesday, the map becomes more favorable to him, with several Western states they argue they can win, including Arizona, which votes March 22.

But to remain viable in a race where Clinton already boasts a commanding lead in the delegate count, Sanders needs to post some strong showings Tuesday.

In Bloomington, Trump’s speech was interrupted several times by protesters, some of whom tore up campaign signs. Each time, Trump ordered them to leave.

“You see where they put themselves? Right in front of the cameras,” he said as one protester was escorted out.

“That’s all they care about,” Trump said. “Disgusting.”

Mary Jane Nelson, a Rubio backer who came to see the senator from Florida at The Villages, summed up her view of Trump succinctly: “I find him very scary.”

Wagner reported from St. Louis, Guarino from Bloomington, Ill. Jose A. DelReal in West Chester, Ohio; David Weigel in Strongsville, Ohio; Abby Phillip in Chicago; Katie Zezima in Concord, N.C.; and Michelle Ye Hee Lee in Washington contributed to this report.