Donald Trump scored victories Tuesday in three states, including the big-prize Florida, but lost Ohio to the state's governor, John Kasich, as the billionaire continued to move ahead in his stunning campaign for the Republican presidential nomination. Hillary Clinton won at least four states, dealing a severe blow to Bernie Sanders' bid to slow her march toward the Democratic nomination.

Marco Rubio, the Florida senator who staked his once-promising campaign on winning in his home state, dropped out of the presidential race shortly after the polls closed. That leaves Kasich as the last true establishment candidate running against Trump and arch-conservative Texas Sen. Ted Cruz.

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Trump, the brash and controversial reality TV star, has upended Republican politics by winning most of the state-by-state competitions for delegates who will choose the party's nominee. He has seized on Americans' anger with Washington politicians, discomfort with immigration and fears of terrorism, attracting voters with his blunt talk and simply worded promise to make America great again.

Tuesday's votes in five states had been viewed as a pivotal moment in the Republican presidential campaign. For the first time, two states — Ohio and Florida — had winner-take-all contests. A Trump sweep could have given him an insurmountable lead in the delegate count.

Trump won the biggest prize — all 99 Florida delegates — as well as winning North Carolina and Illinois, and was locked in a tight race with Cruz in Missouri. He told a victory rally in Florida, "This was an amazing night."

But Kasich's win, capturing all of Ohio's 66 delegates, was crucial to keeping alive the hopes of mainstream Republicans trying to stop Trump.

Trump responds after U.S. primaries0:46

Missouri too close to call

Both the Republican and Democratic primaries in Missouri were too close to call Wednesday morning.

While Trump has amassed the most delegates, he's winning just 46 per cent of the delegates that have been awarded so far. If that pace continues, he would fall short of the majority that he would need to assure him the nomination at the party's convention in July. The result could be a contested convention, creating an unpredictable outcome.

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Republican U.S. presidential candidate Marco Rubio announced the suspension of his presidential campaign during a rally in Miami, Fla., on Tuesday. (Carlo Allegri/Reuters)

This was the first victory for Kasich, whose upbeat message and long record of government service has had little resonance as his rivals seized on voters' anxiety and disdain for Washington. While he could benefit from Rubio dropping out, he remains an extreme longshot for the nomination, though he could help keep Trump below the 50 per cent threshold.

Cruz said at a Houston rally that the battle for the Republican presidential nomination battle was a "two-person race" between himself and Trump. He did not mention Kasich by name.

Trump now has 621 delegates. Cruz has 396 and Kasich 138. Rubio left the race with 168 delegates. It takes 1,237 delegates to win the Republican nomination for president.

Clinton takes commanding lead

In the Democratic race, Clinton's victories in Florida and North Carolina were expected, but Sanders, a Vermont senator and self-described democratic socialist, had hoped to take the industrial states of Ohio and Illinois, both of which Clinton won. He criticized the former secretary of state for her past support for trade deals. Sanders is unlikely to overtake Clinton in the delegate count, but his victory last week in Michigan underscored the unease that many Democratic voters have about her candidacy.

Clinton responds after U.S. primaries1:39

With her wins Tuesday, Clinton put herself in a commanding position to become the first woman in U.S. history to win a major party nomination.

Overall, Clinton has at least 1,561 total delegates including superdelegates, who are elected officials and party leaders free to support the candidate of their choice. Sanders has at least 800 delegates when the count includes superdelegates. It takes 2,383 to win the Democratic nomination.

In Missouri, the margins between Trump and Cruz and between Clinton and Sanders, were less than one-half of 1 percentage point, meaning the losing candidate can request a recount. The Associated Press did not call either race.

At a victory rally in West Palm Beach, Florida, Clinton pivoted quickly to the November election by assailing Trump's hardline immigration positions and support for torture. "Our commander-in-chief has to be able to defend our country, not embarrass it," she declared.

Rubio rebuked Trump

Trump has alienated many Republicans and Democrats alike with his disparaging remarks about Mexicans, Muslims and women, among others. He entered Tuesday's primaries embroiled in one of the biggest controversies of his contentious campaign. He has encouraged supporters to confront protesters at his events and is now facing accusations of encouraging violence after skirmishes at a rally last week in Chicago that he ended up cancelling.

"I don't think I should be toning it down because I've had the biggest rallies of anybody probably ever," Trump said Tuesday on ABC's "Good Morning America." `'We have had very, very little difficultly."

Sanders responds after U.S. primaries1:56

Rubio and Kasich have suggested they might not be able to support Trump if he's the nominee, an extraordinary stance for intraparty rivals. All of the Republican candidates had earlier pledged to support the nominee.

Rubio implicitly rebuked Trump throughout a speech in Miami announcing he was dropping out of the race, imploring Americans to "not give in to the fear, do not give in to the frustration."

Now thrust into the center of a campaign that has been bitingly personal, Kasich vowed to cheering supporters in Berea, Ohio, that he would "not take the low road to the highest office in the land."

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Democratic U.S. presidential candidate Hillary Clinton waves as she speaks to supporters at a campaign rally in West Palm Beach, Fla., on Tuesday. (Carlos Barria/Reuters)

Trump has been the target of millions of dollars in negative advertising in recent weeks, including one ad campaign that highlights his statements that appear to encourage violence — among them, "I'd like to punch him in the face."

Corrections

  • An earlier version of this story incorrectly said that Tuesday's primaries could give Donald Trump more than 1,237 delegates, allowing him to secure the Republican nomination.
    Mar 15, 2016 6:40 PM ET