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Story highlights

Five states hold their Republican and Democratic primaries on Tuesday: Florida, Illinois, Missouri, North Carolina and Ohio

The 99-delegate Florida and 66-delegate Ohio are winner-take-all contests

Hillary Clinton is all but assured of finishing her sweep of the South by picking up wins in Florida and North Carolina

Bernie Sanders will try to replicate his stunning victory in Michigan last week by winning similar big, manufacturing-heavy, states: Illinois, Missouri and Ohio

Columbus, Ohio CNN —  

For Republicans dead set on stopping Donald Trump, Tuesday represents a final chance to seriously impede his path to the party’s presidential nomination.

On the Democratic side, it’ll be yet another test of Hillary Clinton’s organizational strength and backing among party loyalists against Bernie Sanders’ ability to expand the electorate and win in diverse states.

Five states hold their Republican and Democratic primaries on Tuesday: Florida, Illinois, Missouri, North Carolina and Ohio.

READ: What are each candidate’s odds on Super Tuesday 3?

The contests follow a weekend full of animated protests at Trump rallies – some of which turned violent – and a Democratic town hall where the two candidates lambasted the GOP front-runner for inciting “political arson.”

With so much on the line, the so-called Super Tuesday 3 is shaping up to be a crucial night in the 2016 presidential race.

The Republicans

Raising the stakes on the Republican side is that Florida, with its 99 delegates and Ohio, which awards 66 delegates, are winner-take-all contests.

That means for the two home-state candidates, Ohio Gov. John Kasich and Florida Sen. Marco Rubio, anything short of wins in their own backyards could leave them so far behind in the delegate count that they’d face intense pressure to end their campaigns.

A sweep by Trump would mean all that would be left are extraordinary measures – like a contested convention. And even that could be out of reach.

READ: Why today changes everything for Republicans

So in Ohio, Kasich’s friends in the GOP establishment are pulling out all the stops.

Former House Speaker John Boehner endorsed his fellow Ohioan at a Butler County Republican Party event. He said the two had spent 18 years together in Congress, and he’d already voted early for Kasich.

“He’s my friend,” Boehner said.

Mitt Romney, the 2012 Republican nominee who has recently become one of Trump’s chief antagonists, will hit the campaign trail alongside Kasich in the run-up to Ohio’s primary.

READ: Mitt Romney to campaign with John Kasich

Polls show Kasich and Trump close in the Buckeye State.

And the contest in Ohio comes just a week after Kasich finished third in Michigan – a state with similar demographics, and where he spent a good bit of time campaigning.

In Florida, the situation is more dire for Rubio, who polls show trailing Trump by a 2-to-1 margin.

Nightcap: Trump on violent clashes: I ‘should get credit, not be scorned’ | Sign up

His campaign has long argued that the more moderate states that vote later in the process is where Rubio would have his best showings. But a loss in Florida would put Rubio at risk of seeing his fundraising grind to a halt as he falls further behind in the delegate count.

Rubio spent Sunday making the case that Tuesday’s contests are all about stopping Trump – and arguing that blocking Trump is still possible.

“I think we’re having a battle to define conservatism in the Republican Party,” he said on ABC’s “This Week.” “I do not want the Republican Party or the conservative movement to be defined by what I’m seeing out of Donald Trump’s campaign.”

READ: Marco Rubio’s final Florida push

Rubio said the mathematical path to the nomination, even for Trump, remains daunting.

“Despite all this noise that’s out there, he needs 60% of the delegates from this point forward in order to be the nominee. Ted Cruz by the way needs 75% of the remaining delegates to be the nominee. That’s the real math,” Rubio said. “I at the end of the day do not believe that Donald Trump will be our nominee and I’m going to do everything possible to keep that from happening and to give the party a choice in me, someone that people aren’t going to have to be asked that question about.”

Texas Sen. Ted Cruz doesn’t lead the polls in any of the five states, but Tuesday’s contests will once again test the strength of his campaign’s data and organizational capabilities.

There are opportunities for Cruz to rack up delegates – particularly in down-state Illinois congressional districts, Missouri and North Carolina. His campaign has been carefully calibrating his schedule to seize on those opportunities – which means he’ll try to stay close to Trump in the delegate count even without winning a state.

Cruz’s argument is about electability. He said on ABC’s “This Week” that a Trump nomination would be “a disaster for Republicans, for conservatives. I think it’s a disaster for the country because if Donald is the nominee, it makes it much, much more likely that Hillary Clinton wins the general.”

READ: Ted Cruz allies ‘mystified’ over super PAC sitting on $10 million

Trump said Sunday on CNN’s “State of the Union” that he’s not sweating his GOP rivals.

“They are losing big league,” he said.

He added, “In Florida, we have a man, Marco Rubio, who doesn’t even show up to vote in the U.S. Senate. He’s a disgrace. He’s weak, very weak on illegal immigration, wants to give amnesty to everybody. He’s a person that I don’t think he could be elected dogcatcher in Florida, frankly.”

Of Kasich, Trump said: “If you look at Ohio, we have a man that voted for NAFTA. NAFTA has destroyed Ohio.”

The Democrats

Clinton is all but assured of finishing her sweep of the South by picking up wins in Florida and North Carolina.

The real battleground will be the Midwest. Sanders will try to replicate his stunning victory in Michigan last week by winning similar big, manufacturing-heavy, states: Illinois, Missouri and Ohio.

It’s an especially important set of contests because Clinton’s allies hope she can deliver a knockout blow before the race shifts west, to states where Sanders expects he’ll be more formidable.

As they made their final pitches in Ohio at a CNN town hall Sunday night, both candidates focused on how they’d take on Trump.

Clinton played up her tenure as secretary of state in arguing that Trump’s incendiary rhetoric undermines “our standing in the world.”

“I’m having foreign leaders ask if they can endorse me and stop Donald Trump,” she said.

She reminded the audience that so far in the primary process, she’s received more votes than anyone else – including Trump and Sanders.

And she said she’s the best bet to stand up to Trump in the general election because the Republicans who have “been after me for 25 years” have already thrown the entire book at her.