A new U.S. political survey shows billionaire real estate mogul Donald Trump taking command in the race for the Republican presidential nomination, with former Secretary of State Hillary Clinton grabbing a strong lead in the Democratic contest.
CNN/ORC said 49 percent of Republicans support Trump, more than his four remaining challengers combined. His closest opponent, Florida Senator Marco Rubio, is at 16 percent, followed by Texas Senator Ted Cruz at 15 percent.
In the Democratic race, the poll showed Clinton, the country's top diplomat from 2009 to 2013, with a widening lead over her lone opponent, Vermont's democratic socialist Senator Bernie Sanders, 55 to 38 percent.
Both Republicans and Democrats are getting set for nominating contests Tuesday in 11 states, the biggest electoral day so far in the months-long campaign.
Trump is favored in 10 of the states on what is called "Super Tuesday," all except in the southwestern state of Texas, where Cruz hopes to win on his home turf.
Clinton is looking to capture the majority of the contests she faces against Sanders, who has campaigned against the country's growing income inequality and the clout of giant Wall Street financial firms.
The Republican nomination race has quickly evolved into a taunting, name-calling contest, with Rubio and Trump disparaging each other's physical traits.
Republican presidential candidate Donald Trump gestures during a rally at Radford University in Radford, Va., Feb. 29, 2016.
Trump often refers the Florida lawmaker as "Little Marco Rubio," who "trowels" on makeup to hide his pronounced ears and says he "couldn't get elected dogcatcher."
Rubio on Sunday made light of Trump's "little hands" and a bad "spray tan" on his face.
In recent days, Rubio has derided Trump as a "con artist" trying to hijack the Republican party.
Establishment Republican figures, many of whom have endorsed Rubio and vowed not to support Trump, are worried that he would not be able to defeat Clinton in November's national election and that Republicans would sustain significant losses in Congress, where they now control both the Senate and the House of Representatives.
U.S. Democratic presidential candidate Hillary Clinton rallies with supporters at Wood Museum of Springfield History in Springfield, Mass., Feb. 29, 2016.
"Remember: Friends do not let friends vote for con artists," Rubio warned at one rally.
Rubio also derided Trump's refusal Sunday on a CNN news show to disavow support offered him by David Duke, a former leader of the racist Ku Klux Klan.
Although he answered the questions clearly Sunday, Trump on Monday claimed that the television network had given him a "very bad earpiece" that led to his confusion. Trump said he had disavowed Duke's support in other forums "all weekend long."
Super Tuesday predictions
Rubio is not predicting victory in any of the states voting Tuesday, instead hoping to win delegates to the party's July national presidential nominating convention that will be apportioned state by state based on the vote counts.
He is aiming for his first nomination victory in the winner-take-all contest March 15 in Florida, his home state in the southeastern U.S.
Cruz is warning that the "Trump train" could be "unstoppable" if he wins big victories Tuesday. Cruz has repeatedly told voters he is the only one to defeat Trump so far, in the first caucus in Iowa, although Trump has subsequently won contests in three other states.
Changing demographics in Virginia
Republicans are focusing on campaigning Monday in the South, which accounts for two-thirds of the delegates that will be awarded Tuesday. Trump is holding events in Virginia and Georgia, while Rubio is campaigning in Arkansas.
Cruz is focusing his efforts on his home state and the 155 delegates at stake there out of the 595 to be awarded in the 11 states.
Clinton, looking to a possible general election against Trump, has also started to aim attacks at him and the remaining Republican contenders, all but ignoring Sanders, her immediate opponent.
"What we can't let happen is the scapegoating, the flaming, the finger pointing that is going on the Republican side," Clinton told voters Monday in Massachusetts. "It really undermines our fabric as a nation. So, I want to do everything I can in this campaign to set us on a different course."
WATCH: Suspense builds before Super Tuesday contests
Candidates Campaign Before Super Tuesday Contests:
Supporters look on as democratic presidential candidate former Secretary of State Hillary Clinton speaks during a "Get Out The Vote" event at the Old South Meeting Hall in Boston, Massachusetts, Feb. 29, 2016.
Democratic presidential candidate former Secretary of State Hillary Clinton speaks during a "Get Out The Vote" event at the Old South Meeting Hall in Boston, Massachusetts, Feb. 29, 2016.
Republican presidential candidate, Donald Trump waves to the crowd during a rally at Radford University in Radford, Virginia, Feb. 29, 2016.
Guests listen to the national anthem during a campaign rally for Republican presidential candidate Donald Trump at the Madison City Schools Stadium in Madison, Alabama, Feb. 28, 2016.
Supporters hold signs for Republican presidential candidate Marco Rubio during a campaign rally at the Intercontinental Buckhead Hotel in Atlanta, Georgia, Feb. 29, 2016.
Republican presidential candidate Marco Rubio holds a campaign rally at the Intercontinental Buckhead Hotel in Atlanta, Georgia, Feb. 29, 2016.
Supporters of Democratic presidential candidate Sen. Bernie Sanders (D-VT) hold sings in support during his speech at the Minneapolis Convention Center in Minneapolis, Minnesota, Feb. 29, 2016.
Democratic presidential candidate Sen. Bernie Sanders (D-VT) speaks to a crowd of supporters at the Minneapolis Convention Center in Minneapolis, Minnesota, Feb. 29, 2016.
U.S. Republican presidential hopeful Sen. Ted Cruz speaks to the media with Texas Governor Greg Abbott and former governor Rick Perry following a campaign rally in Dallas, Texas, Feb. 29, 2016
People attend a rally by Republican presidential candidate Sen. Ted Cruz (R-TX) at Gilley's Dallas the day before Super Tuesday in Dallas, Texas, Feb. 29, 2016.
Ohio Governor and Republican presidential candidate John Kasich speaks at an event at Plymouth Memorial Hall in Plymouth, Massachusetts, Feb. 29, 2016.
Republican presidential candidate retired neurosurgeon Ben Carson speaks at the National Religious Broadcasters convention in Nashville, Tennessee, Feb. 26, 2016.