It's Judgment Day for the Republican Party.
On Tuesday, voters are hitting the polls in five states and one territory in contests that could determine whether Donald Trump is on track to win the nomination outright, or whether the GOP faces a bitter convention fight in Cleveland this July.
The vote takes place amid escalating left-wing protests against Trump and escalating rhetoric from the candidate who rivals complain is inciting his backers to violence. Trump cancelled a rally on Friday in Chicago as clashes erupted between protesters and supporters in and outside his event, raising concerns of mounting chaos as the convention and general election near.
The two biggest prizes are winner-take-all states Ohio and Florida, which combine for 165 delegates. Candidates also have a chance to gain ground in North Carolina (72 delegates), Illinois (69 delegates), and Missouri (52 delegates), especially if they earn decisive margins.
A candidate needs 1,237 delegates to clinch the nomination. Trump currently has 460, ahead of Senator Ted Cruz's 369, Senator Marco Rubio's 163, and Ohio Governor John Kasich's 63. By the time the votes are counted Tuesday night, almost 60 percent of GOP delegates will have been awarded and Trump has a good chance of avoiding a contested convention with victories in Ohio and Florida.
Of the two major contests, Florida looks the most favorable to Trump. An NBC News/Wall Street Journal showed him nearly doubling the numbers of his closest competitor, with 43 percent support to just 22 percent for Rubio, who has held elected office in the state almost continuously since 2000.
Nearly every poll going back months shows similar deficits for Rubio. If he wins, it will be an upset for the ages. If he loses, it will be difficult to continue his campaign, which has crashed and burned in recent state contests as Cruz, who campaigned in Florida last week, absorbs his support.
Trump campaigned in Tampa on Monday with Sarah Palin and the state's attorney general Pam Bondi, who endorsed him onstage. Referring to recent protests, Palin decried that "petty, punk-ass little thuggery stuff." Trump urged voters to rally behind him in Ohio and Florida, as it would give him a chance to put the race away early and "focus on Hillary" instead of his GOP rivals.
Rubio has taken a more reflective tone in recent appearances as he warns that Trump is sowing "anarchy" and "chaos" that could do generational damage to the party and to the country.
"I don't think there's anyone in the history of American politics that compares to the vulgarity of a Donald Trump candidacy," Rubio told the press in Melbourne, FL on Monday.
In a highly unusual move for a candidate, Rubio has called on his own supporters to vote for Kasich in Ohio to help deny Trump the state's delegates. Kasich has not reciprocated with a similar call to his own voters in Florida.
While Kasich does not have a particularly realistic path to the nomination outside of a contested convention, his odds look better in his home state of Ohio than Rubio's do in Florida. An NBC/WSJ poll this week put him up 39-33 over Trump, and other recent polls show Kasich either leading by a small margin or tied.
Kasich campaigned with Mitt Romney Monday in North Canton, where he touted his record guiding Ohio in the aftermath of the financial crisis and said he would not attack his opponents - even Trump, who has savaged him all week.
"Ohio should send a message to the country, and when I win Ohio it is going to send such a positive message to the world," Kasich said.
While Cruz is unlikely to win in Ohio and Florida, his campaign has carefully targeted individual congressional districts in Illinois and Missouri that they hope give him the best chance of yielding delegates. Both races are considered competitive and an NBC/WSJ poll of Illinois Republicans this week showed Trump leading with 34 percent to 25 percent for Cruz and 21 percent for Kasich.
Cruz has trained his fire on Trump in recent speeches, citing his donations to Democratic politicians like former Illinois Governor Rod Blagojevich, who was convicted on corruption charges, and Chicago Mayor Rahm Emanuel.
"Now help me on this: Have you ever sat on your couch and been like, 'I'll give this money to Blago or I'll give $50,000 to Rahm?" Cruz asked voters in Rockford, Illinois on Monday.