Donald Trump's Super Tuesday victory gives the outsider a commanding lead in his bid for the Republican presidential nomination, at the same time stoking the fight in the party over his divisive campaign.
The billionaire businessman and reality-television star won seven states, including vote-rich Georgia, Massachusetts and Virginia, and at least 203 delegates.
Canadian-born Texas Senator Ted Cruz, however, pulled out wins in his home state, Oklahoma and Alaska, allowing him to fight another day. Florida Senator Marco Rubio, for his part, notched up a victory for the first time in the contest by taking Minnesota; he also finished just four points behind in Virginia. And Ohio Governor John Kasich fought Mr. Trump to a virtual draw in Vermont, coming within two points of a win.
The results will ensure that Mr. Trump continues to face a dogfight with both the party's hard-right and establishment wings as he seeks to build up his lead.
Speaking to supporters at the Redneck Country Club – yes, that is actually its name – a bar in suburban Houston, a jubilant Mr. Cruz called for all the other Republican candidates to drop out and support his bid.
"Tomorrow morning we have a choice: so long as the field remains divided, Donald Trump's path to the nomination remains more likely and that would be a disaster for Republicans," he said. "I ask you to prayerfully consider our coming together. United."
Mr. Cruz's Texas victory was something of a mixed bag: While the 155-delegate state was the night's biggest prize, he fell short of the 50-per-cent threshold needed to take all the delegates, meaning he will have to share some with Mr. Trump.
Mr. Rubio's Minnesota victory breathed new life into his campaign, giving party brass reason to hope they will not have to choose between two outsiders – Mr. Trump and Mr. Cruz – in the race.
"This is a fight for the heart and soul of the Republican Party – I will go through all 50 states," the Florida senator declared in an interview with CNN. "If we nominate Donald Trump, it will be the end of the modern Republican Party. Hillary Clinton will smoke him in the general election."
Mr. Rubio faces his most crucial test March 15, when his home state holds its primary.
Despite his big victory, Mr. Trump's lead is not as strong as that of Democratic front-runner Hillary Clinton, who has won a string of convincing victories over challenger Bernie Sanders. While Ms. Clinton has all but sewn up her nomination, Mr. Trump still faces a long slog and an expanding list of Republicans who want him defeated at all costs.
Mr. Trump took aim at Ms. Clinton in his victory speech, before going on a lengthy rant about American corporations that have moved manufacturing plants overseas.
"She's been [in Washington] for so long, if she hasn't straightened it out by now she won't sort it out in the next four years," he said in Palm Beach, Fla.
"Our nation is in serious trouble. We're being killed on trade. China is just taking advantage of us. I have nothing against China but their leaders are smarter than our leaders," Mr. Trump said. "We're going to create jobs like you've never seen."
But he also made an attempt to seem more presidential, congratulating Mr. Cruz for taking Texas and promising to unite the party.
"I congratulate Ted Cruz on that win, it was an excellent win," he said. "I am a unifier -- I would love to see the Republican party get together."
Mr. Trump's seemingly unstoppable ascent is deeply dividing the GOP, with some leaders even floating the possibility of a splitting off from the party if he takes the nomination.
"My current answer for who I would support in a hypothetical matchup between Mr. Trump and Mrs. Clinton is: Neither of them. I sincerely hope we select one of the other GOP candidates, but if Donald Trump ends up as the GOP nominee, conservatives will need to find a third option," Republican Senator Ben Sasse, a Nebraska Tea Partier, wrote on Facebook Sunday.
And Mel Martinez, former Republican National Committee chairman, told the Wall Street Journal Monday: "I would not vote for Trump, clearly. If there is any, any, any other choice, a living, breathing person with a pulse, I would be there."
Mr. Trump's supporters see in him a savvy businessman who will use his tough-guy attitude to shake up the country's deadlocked politics.
But his detractors see him as a blustering false prophet, whose outlandish promises – a wall along the Mexican border, the deportation of millions of illegal immigrants and a ban on Muslims entering the country – are merely cynical attempts to push hot button issues.
"Trump is all talk. He's trying to insult his way to the White House," said Martha Matula, a 56-year-old property manager after casting her ballot for Mr. Cruz at the Encourager Church, a boxy brown building next to an elevated expressway in the western suburbs of Houston.
Ms. Matula said she trusted Mr. Cruz to make progress on the issues she cares about: fighting illegal immigration and protecting the right to bear arms.
"I immigrated from Mexico. I waited and went through the process. I've never been on welfare in my life; I have a college degree. If I waited, everybody else can wait too," she said. "I carry a weapon. I believe in using a gun when I need to – obviously, legally and carefully."
Jill Fairchild said she cast her ballot for Mr. Cruz, attracted by his anti-abortion, small-government pitch. Mr. Trump, she said, comes off as insincere. He previously espoused pro-choice, pro-universal health-care views before pulling an abrupt U-turn when he decided to run for president.
"Everything he says is way crazy, is out there – like he's just saying what he thinks is going to get people to vote for him," the 58-year-old math tutor said. "But who knows what he's actually going to do in the end."
But Trump supporter Greg Cox, 63, said Mr. Trump's previous Democratic ties are actually an asset.
"You're getting a non-politician who's been involved in working with both sides of the aisle," he said, leaning against the tailgate of his silver pickup truck in the church parking lot. "I don't agree with everything the Republican Party has got to say and I don't believe in everything the Democratic Party has got to say. So in a way it's refreshing to see somebody that does business with both sides."
An unemployed oil-field worker in a blue checked shirt and jeans, Mr. Cox conceded Mr. Trump is a little over the top. But he said he believes he will follow through on promises to crack down on illegal immigration and re-establish the United State' strong place in the world.
"I don't necessarily like his arrogance and he's been a little bit conceited. But I figure all the other candidates are business as usual. At this point I'm desperate to see something different," he said.
James Gaitens, a 62-year-old geophysicist, said that at first he didn't take Mr. Trump's candidacy seriously. But he was eventually convinced by the reality television star's tough stand on immigration.
When asked if the promise of the border wall wasn't a little far-fetched, he scoffed.
"We put a man on the moon – we can build wall across the southern border," he said. "Or the northern border, if we choose to do it."