He leads Cruz 57% to 40%, Trump 55% to 43% and Rubio 53% to 45%.
Republicans face a more daunting challenge in uniting their party, and Nebraska's Ben Sasse, a rising star among conservatives, became the first current senator to raise the prospect of backing a third party option if Mr Trump clinches the nomination.
"I believe that health care is a right of all people, not a privilege", Sanders said to a cheering crowd in Minneapolis on Monday.
Oklahoma and MA are twostates worth watching with close early poll numbers between Sanders and Clinton. RCP's average of polls puts Ted Cruz about 11 points ahead of Trump in Cruz's home state. Ted Cruz, R-Texas poses for a photo with Amanda Reeves and her seven-month-old son Ty Reeves after a campaign rally at the Gilley's nightclub, Monday, Feb. 29, 2016, in Dallas.
Marco Rubio said of Trump, "What he's trying to carry out is a scam to take control of the office of the presidency of the United States". If one candidate gets enough votes, they could walk away with all of the delegates, giving them a big boost.
"On Tuesday, you have a big day", Trump told supporters at a big rally in Tennessee, saying he didn't care if someone was at death's door or if their wife was leaving them-they had to vote. Like Mr Trump, she could begin putting her party's nomination out of reach for rival Bernie Sanders with a strong showing on Super Tuesday. Republicans in Alaska will hold caucuses.
While none of the candidates can leap a building in a single bound, Donald Trump and Hillary Clinton will be looking to leap above their competition in the race to the nomination.
Registered voters in Virginia may vote in either primary (but not both), meaning the state's Super Tuesday nominating contests could serve as a proxy for the November general election.
Republican presidential candidates, Sen.
The biggest chunks of delegates up for grabs are concentrated in southern states - Alabama, Arkansas, Georgia, Tennessee, and Texas - which is why Super Tuesday is sometimes referred to as the "SEC primary" after the collegiate athletic conference with member schools in those states. Marco Rubio and John Kasich have vowed to stay in until the March 15 primaries in their home states - Florida and OH, respectively.
The Florida senator has cast himself as the Republicans' best chance to win in a general election and has received a flood of endorsements from party officials after other more mainstream candidates dropped out. On the Democratic side, Bernie Sanders is hoping to pull out some wins, including in his home state of Vermont.
The colourful campaign of the billionaire, who won three of the four early voting states, has divided Republicans. Their reluctance foreshadowed a potentially extraordinary split in the party this autumn.
In the latest controversy, Trump came under withering criticism for not immediately disavowing the support of David Duke, who once led the Ku Klux Klan.
Trump also said he's bringing new people even Democrats into the Republican Party.
The two parties have different strategies for reaching overseas voters.