Donald Trump
Donald TrumpPhoto: im Young, Reuters

It's Super Tuesday and Democrats are holding primaries in 12 states, while Republicans vote in 11.

Lead Republican candidate Donald Trump on Tuesday called on Marco Rubio to drop out of the 2016 presidential race if he doesn’t do well on Tuesday.

“I think he has to get out,” Trump told Fox News in a telephone interview. “You know, he hasn’t won anything, and Ted Cruz very rightly points out, you know, Marco has not won.”

Trump won in New Hampshire, South Carolina and Nevada, and Cruz won the Iowa caucuses and is expected to win Texas. Rubio has yet to win a state, but he expects to be victorious in his home state of Florida on March 15.

 “Little Marco Rubio, let me tell you, he’s been a disaster for Florida… honestly, I don’t think he could be right now elected a dog catcher in Florida," Trump said acerbically.

For Democrats, the polls are being held in Alabama, American Samoa, Arkansas, Colorado, Georgia, Massachusetts, Minnesota, Oklahoma, Tennessee, Texas, Vermont and Virginia, with 865 delegates at stake.

Republicans are voting in Alabama, Alaska, Arkansas, Georgia, Massachusetts, Minnesota, Oklahoma, Tennessee, Texas, Virginia and Vermont, with 595 delegates at stake.

Republican candidates need 1,237 delegates to win the party's nomination, and Democrats need 2,383.

An NBC/WSJ poll showed Trump leading in Tennessee and Georgia and a Roanoke College poll also has him ahead in Virginia. Competitors Rubio and Cruz have repeatedly found themselves in second and third place behind Trump, and Tuesday's polls will be crucial for both of them.

"If we nominate him [Trump], let me just tell you a vote for Donald Trump tomorrow is literally a vote for Hillary Clinton in November and it cannot happen," said Rubio at a campaign event in Jenks, Oklahoma, on Monday.

Cruz said Trump should clarify reports from news website BuzzFeed, according to which Trump had suggested to the New York Times' editorial board in an off-the-record briefing on January 5 that he would most likely not stand by his anti-immigration proposals if elected president.

He also attacked Trump's past campaign donations. "You don't get to fund open-border Democrats for four decades and then suddenly when you run for president discover and announce you're for securing the border," Cruz said.