Republican Donald Trump and Democrat Hillary Clinton swept through the South on Super Tuesday, claiming victory in their parties' primaries in delegate-rich Georgia, Tennessee, Alabama and Virginia. The front-runners appeared ever more likely to end up in a general election showdown.
Democrat Sen. Bernie Sanders won four states. Republican Sen. Ted Cruz won three state contests while Sen. Marco Rubio picked up his first win.
Cruz won his home state of Texas, the night's single biggest prize, as well as neighbouring Oklahoma and Alaska.
Sanders picked up his home state of Vermont, as well as Oklahoma, Colorado and Minnesota, but failed to broaden his appeal beyond youth voters in most cases.
Overall, the night belonged to Trump and Clinton, who turned the busiest day of the 2016 primaries into a showcase of their strength with a wide swath of American voters.
Signalling her confidence, Clinton set her sights on Trump as she addressed supporters during a victory rally.
"It's clear tonight that the stakes in this election have never been higher and the rhetoric we're hearing on the other side has never been lower," she said.
Trump, too, had his eye on a general election match-up with the former secretary of state, casting her as part of a political establishment that has failed Americans.
"She's been there for so long," Trump said at his swanky Mar-a-Lago resort in Florida. "If she hasn't straightened it out by now, she's not going to straighten it out in the next four years."
Clinton is the winner in seven states -- Massachusetts, Texas, Virginia, Georgia, Alabama, Tennessee and Arkansas -- states which give the winner a significant number of delegates at the Democrats' nomination convention this summer. She also won the caucuses in American Samoa.
Trump has also taken seven states -- Massachusetts, Virginia, Georgia, Alabama, Virginia, Vermont and Tennessee.
"What a Super Tuesday!" said Clinton, smiling broadly, at a rally in Miami as the results came in. "All across our country today, Democrats voted to break down barriers so we can all rise together."
Trump won at least 203 delegates Tuesday. Cruz collected at least 144 delegates and Rubio picked up at least 71. Overall, Trump leads with 285 delegates, Cruz has 161, Rubio has 87, Kasich has 25 and Carson has eight. It takes 1,237 delegates to win the GOP nomination.
Clinton is well on her way to the 2,383 delegates needed on the Democratic side.
Her victory speech shifted its focus toward the general election. Instead of criticizing her socialist primary rival Sanders, she tore into her Republican rival.
"I believe what we need in America today is more love and kindness. Instead of building walls, we're going to break down barriers and build ladders of opportunity," Clinton told a boisterous crowd in Florida.
As Trump's victories piled up, he fired off "thank you" Twitter notes to the states that landed in his win column.
Sanders reminded supporters that for now delegates are still being awarded proportionally — and he remained poised to gain plenty Tuesday, despite losing most states aside from a dominant performance in his home of Vermont.
He vowed to keep campaigning through the spring. In a punchy address to the home crowd, he reminded his longest-standing supporters of how much they'd advanced since he launched his campaign by a Vermont lake.
"We were at three per cent in the polls. We have come a very long way in 10 months," said Sanders.
"At the end of tonight, 15 states will have voted. Thirty-five states remain. Let me assure you that we are going to take our fight for economic justice, for social justice, for environmental sanity, for a world of peace, to every one of those states."
But early exit polls underscored Sanders' continued weaknesses with black voters, a core part of the Democratic constituency. Clinton led with African-Americans, as well as both men and women, in Georgia and Virginia, according to surveys conducted by Edison Research for The Associated Press and television networks.
Cruz desperately needed a win in Texas in order to stay in the race, and was likely to keep campaigning as the only Republican who has been able to defeat Trump in any primary contest.
For Florida Sen. Marco Rubio, the night was turning into a disappointment. While a flood of Republican officeholders have rallied around him in recent days, his first victory remained elusive as results rolled in.
Still, Rubio, who has launched an aggressive campaign to stop Trump in recent days, vowed to keep up his efforts to "unmask the true nature of the front-runner in this race."
The Florida senator's long-shot White House hopes now rest with his home state, which votes on March 15. But he's expected to face fresh calls from Trump and others to drop out of the race before then.
"He has to get out," Trump told Fox News earlier in the day. "He hasn't won anything."
Democrats were voting in 11 states and American Samoa, with 865 delegates up for grabs. Republicans were voting in 11 states, with 595 delegates at stake.
The possibility of a big night for Trump would intensify worries among Republican leaders who fear the billionaire could inflict long-term damage on the party.
Trump, the brash billionaire and reality TV star, has stunned the Republican political establishment by winning three of the first four contests, seizing on the anxieties of voters angry at Washington and worried about terrorism, immigration and an uncertain economy. Using simple terms, and often coarse language, he has soared to the top of polls with his pledge to "make America great again."
Republican officials, fearing a Trump sweep, have been lashing out at his temperament and command of the issues in the hours before voting began.
"You've got a con man and a bully who is moving forward with great speed to grab the party's mantle to be its standard bearer," Norm Coleman, a former senator who backs Marco Rubio, said in an interview with The Associated Press. "That's almost incomprehensible."
Clinton, once seen as the all-but-inevitable Democratic nominee, has contended with an unexpectedly strong challenge from Bernie Sanders, a Vermont senator and self-described democratic socialist. But Clinton, like Trump, has also won three of the first four races, and a landslide victory in South Carolina on Saturday bodes well for prospects in important southern states Tuesday due to her overwhelming support among black voters.
Elections were being held Tuesday in 12 of the 50 U.S. states. Candidates vie to win delegates who will vote for them at the parties' conventions in July. For Republicans, 595 delegates were at stake, nearly half of the 1,237 needed for the nomination. Democrats were allocating 865, delegates more than one-third of the 2,383 needed to become the nominee.
Both Cruz and Rubio have launched furious verbal attacks on Trump in recent days, but some in the party establishment fear the anti-Trump campaign has come too late.
Cruz once saw the Southern states that vote Tuesday as his opportunity to stake his claim to the nomination, given their large evangelical Christian populations, only to see Trump pick up a sizable segment of evangelicals.
Rubio's goal is even more modest. He's seeking to stay competitive in the delegate count and hoping to pull off a win in his home state of Florida on March 15.
Ohio Gov. John Kasich and retired neurosurgeon Ben Carson remain in the race.
Republicans spent months largely letting Trump go unchallenged, wrongly assuming that his populist appeal with voters would fizzle. Instead, he appeared to only grow stronger, winning states and drawing support for some of his most controversial proposals.
In six of the states voting Tuesday, large majorities of Republican voters said they supported a proposal to temporarily ban all non-citizen Muslims from entering the United States, an idea championed by Trump. The exit polls were conducted by Edison Research for The Associated Press and television networks.
The worries among Republicans appeared to grow after Trump briefly refused to disavow the apparent support of former Ku Klux Klan leader David Duke during a television interview. Trump later said he had not understood the TV interviewer who had first raised the question about, and he did repudiate him.
With reports from The Associated Press, Reuters and The Washington Post.