John Bacon

USA TODAY

McLEAN, Va. — Democratic presidential hopeful Hillary Clinton ripped Republican "bigotry and bullying," GOP frontrunner Donald Trump urged a foe to abandon his bid and voters in a dozen states marched to primary polls as the race for the White House roared into Super Tuesday.

Clinton and Trump sought to consolidate leads while longshot hopefuls fought to stay relevant. At stake Tuesday: The biggest one-day total of convention delegates in the 2016 primary season.

Trump, Sens. Marco Rubio and Ted Cruz, Ohio Gov. John Kasich and physician Ben Carson were competing for 595 GOP delegates, almost half the 1,237 needed to win the presidential nomination. Clinton and Sen. Bernie Sanders were sparring for 865 delegates plus 150 unpledged "super" delegates, or about a third of the number needed to claim the party's nod.

"I speak out against bigotry and bullying wherever I hear it, and I hear a lot of it from Republican candidates," Clinton told reporters Tuesday. "They seem to have forgotten completely about the issues and are running campaigns on insults. It's turned into a one-upmanship on insulting."

Trump was predicting a landslide day that would all but end the Republican contest. He dismissed recent polls showing he would not fair well against Clinton in a general election, and he suggested Rubio exit the race if the Floridian did not win a state Tuesday.

“I think he has to get out," Trump told Fox and Friends on Tuesday. "He hasn’t won anything. ... I think he is 0 for 18.”

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Rubio blasted back at a rally, calling Trump a "con artist" and "an embarrassment to America."

Both parties are conducting primaries in Alabama, Arkansas, Georgia, Massachusetts, Oklahoma, Tennessee, Texas, Vermont, and Virginia, as well as caucuses in Colorado and Minnesota. The GOP also will hold a caucus in Alaska; Democrats in American Samoa.

Texan Cruz was fighting to wrench the bulk of his state's 155 delegates from the Trump camp, a crucial step on the Cruz path toward a possible nomination. If the winner claims more than half the vote, he will also claim all 47 statewide delegates. Otherwise, those delegates will be apportioned among candidates claiming more than 20% of the vote. A similar system is in place for the three delegates from each of the state's congressional districts.

Kasich has pledged to remain in the race at least until the Ohio primary in two weeks. Carson, whose polling numbers have faded in recent months, continued to fend off questions about when he will drop out.

On the Democratic side, the Clinton campaign was hoping to run up an insurmountable lead by earning roughly 500 delegates on Tuesday. That would require Sanders to win 53% of the remaining delegates in remaining elections simply to tie Clinton, according to Cook Political Report analyst David Wasserman.

Polls show Clinton favored to win most of Tuesday's contests, including a recent Suffolk University poll showing her in the lead in Massachusetts, one of a handful of state’s Sanders was hoping to carry. Clinton's confidence has been reflected in recent campaign speeches targeting the GOP, not Sanders.

“Republicans want to sell the same snake oil, they want to go back to trickle-down economics,” Clinton said during a rally Monday at George Mason University in Fairfax, Va.

Hillary Clinton, Donald Trump lead in Virginia ahead of Super Tuesday

Brooke Adams, 18, from Norfolk, Va., was voting at her high school before soccer practice.

Adams said she voted for Rubio. She said that since she was certain Clinton would get the Democratic nomination, she wanted to use the open primary to stop Trump.

"I've known for a while that I would vote for a nominee just to not see Donald Trump get the nomination," Adams said.

Jennifer Atwater, 34, from Virginia Beach, Va., supported Clinton in 2008, but said she was voting for Sanders.

"Hillary just doesn't stand for what she used to," Atwater said. "She's in the pockets of way too many people now and that's not what Bernie's about."

For his part, Sanders has been undeterred by recent losses in Nevada and South Carolina. The inoclastic Vermonter, who claimed independent status through most of his career but generally aligned with Democrats, remains a fundraising powerhouse. He raised more than $40 million in February alone.

Sanders continues to stump for big-ticket items such as free tuition for public universities and a Medicare-for-all health care system. He has stepped up efforts to distinguish himself from Clinton, who has positioned herself as the realist in the race and has said she doesn’t want to make promises she can’t keep.

Sanders says that when you run on a platform calling for a full loaf, “at worst you’re going to get a half loaf.”

But if you ask for a half loaf, “you’re gonna get crumbs.”

Contributing: Heidi Przybyla, David Jackson, Nicole Gaudiano, Natalie Escobar, Jack Corrigan, and Mariana Alfaro and Sabrina Rodriguez