(Reuters) - Republican Donald Trump and Democrat Hillary Clinton rolled up a series of big primary wins on Tuesday, as the two presidential front-runners looked to take command of their party nominating battles on the 2016 campaign's biggest night of voting.
U.S. networks projected Trump won five states and Clinton won six states on Super Tuesday, when 12 states were voting. Trump won Alabama, Georgia, Massachusetts, Tennessee and Virginia, while Clinton won Alabama, Arkansas, Georgia, Tennessee, Texas and Virginia.
But Ted Cruz, a U.S. senator from Texas, won his home state and neighbouring Oklahoma, stopping Trump's winning streak and giving hope to Republicans looking for a way to stop Trump's potential rise to the nomination.
Opinion polls heading into the voting had shown Trump leading in most of the 12 states up for grabs, raising the possibility of a big night that would intensify worries among Republican leaders who fear the billionaire could inflict long-term damage on the party.
Exit polls and early results showed Arkansas and Vermont were too close to call for Republicans, networks said. For Democrats, Massachusetts was too close to call.
Clinton, the former secretary of state, hoped to win enough states to take a big step towards wrapping up her nomination fight with rival Bernie Sanders, a democratic socialist U.S. senator from Vermont.
"The stakes in this election have never been higher and the rhetoric we're hearing on the other side has never been lower," Clinton, 68, told supporters in Miami. "Trying to divide America between us and them is wrong, and we're not going to let it work."
Sanders won his home state of Vermont and Oklahoma, two of five states he was targeting for victory on Tuesday. He thanked cheering supporters in his hometown of Burlington, Vermont, and assailed the Republican front-runner.
"We are not going to let the Donald Trumps of the world divide us," said Sanders, 74, adding that he expected to pile up "hundreds" of convention delegates in voting on Tuesday.
Super Tuesday is the biggest single day of state-by-state contests to select party nominees for the Nov. 8 election to succeed Democratic President Barack Obama. Voting stretches from eastern states to Texas and Minnesota.
Trump, 69, has worried many in the Republican establishment with proposals such as building a wall along the U.S. southern border with Mexico, deporting 11 million illegal immigrants and slapping a temporary ban on Muslims entering the country.
But while his campaign has confounded many Republican leaders, the New York real estate developer cites his high poll numbers as proof he is not dividing the party but expanding its ranks. He preached unity as he looked beyond the day's voting to campaign in Ohio, which votes on March 15.
TRUMP LOOKS TO EXPAND LEAD
With a string of victories on Tuesday, Trump would expand his strong lead over Cruz, U.S. Senator Marco Rubio of Florida, Ohio Governor John Kasich and retired neurosurgeon Ben Carson.
Voting with his wife in Houston, Cruz, 45, said he hoped Republicans would see a narrower field emerge on Wednesday.
"For any candidate that wakes up tomorrow morning who hasn't won any states ... I think it's time to start thinking about coming together and unifying and presenting a clear choice," said Cruz, the only Republican to win a state contest besides Trump to date.
Even as Trump advances, many Republican Party leaders do not support him and worry that he would be easily defeated in November if Clinton became the Democratic nominee.
The crossfire between Trump and establishment Republicans threatened to rip the party apart at a time when it will need to generate momentum behind a prospective nominee. That worries some Republican strategists looking ahead to the nominating convention in July.
"If Trump continues winning, disappointed party elites will need to reconcile with supporting the party nominee," said Tim Albrecht, a Republican strategist in Iowa.
On the Democratic side, Clinton took advantage of her strong performance with black voters to cruise to big wins in several Southern states, where blacks make up a big bloc of the Democratic electorate.
In addition to his home state of Vermont, Sanders had been aiming for wins in four other states on Tuesday - neighbouring Massachusetts, Oklahoma, Minnesota and Colorado.
While some Democrats have begun to question whether Sanders should continue his challenge to Clinton, he made it clear that he had no intention of dropping out anytime soon.
"At the end of tonight, 15 states will have voted, 35 states remain," Sanders said in Vermont. "And 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."