U.S. presidential hopefuls from both parties will face their biggest challenge yet this week with Super Tuesday offering up more delegates in a single day than at any other point in the election cycle.

Republican primaries and caucuses will be held in 13 states. On the Democratic side, 11 states, along with American Samoa, will be casting ballots.

Republican frontrunner Donald Trump began campaigning throughout the South last year, when he issued a rallying cry that has long resonated in the region.

"The silent majority is back!" he declared. The message was so well-received that Trump's campaign started distributing signs emblazoned with the phrase at rallies.

Trump's rhetoric harkened back to Richard Nixon's "Southern strategy," a concerted effort to bolster support from working-class white voters in the elections that followed passage of the 1964 Civil Rights Act.

Nixon made frequent references to the "silent majority" and the "forgotten majority." In the years since, his aides have acknowledged that he patterned his approach after George Wallace, Alabama's segregationist governor and a two-time presidential candidate.

'A lot of anger out there,' Trump says

On Sunday, Trump explained his own brand of populism on CNN. "I'm representing a lot of anger out there," he said. "We're not angry people, but we're angry at the way this country's being run [and] angry at the way the Republican Party is being run."

South Carolina Republicans

Donald Trump won all 50 delegates up for grabs in South Carolina, easily outpolling rivals Senator Marco Rubio and Senator Ted Cruz.

Super Tuesday votes give Trump, who won victories in New Hampshire, South Carolina and Nevada, the opportunity to strengthen his lead over closest rivals, Texas Senator Ted Cruz and Florida Senator Marco Rubio.

The lineup Tuesday includes several Southern states that form the core of Cruz's desired path to the nomination, but he finds himself trailing Trump everywhere but his home state of Texas. Rubio does not lead anywhere, leaving the two senators mostly to scramble for second-place finishes and as many delegates as possible.

"I've been an underdog my whole life both in life and in politics and we're going to do well. We're going to pick up a lot of delegates," Rubio said Sunday on CBS. "We're going to be in as many states as it takes to ensure that I'm the nominee."

Southern states crucial

A majority of the states sending delegates to national conventions after this crucial round of voting are in the South and they include Arkansas.

Eight years ago, Democrats were such a dominant force in that sate that Republicans didn't bother putting up a candidate to challenge for a U.S. Senate seat.

Today, the state that launched the careers of generations of centrist Democrats, including former president Bill Clinton, has joined the rest of the South in largely turning its back on the party.

Democrats have control of just one governor's mansion, one Senate seat and no legislative chambers from the Carolinas westward to Texas. That stretch includes five states voting in the Super Tuesday contests, a delegate-rich day that will put the South in the spotlight.

Obama win strengthened Republican hold

The region's flip from Democratic stronghold to Republican bulwark is steeped in decades-old shifts in the national parties. But it's also accelerated under President Barack Obama, an urbane, African-American politician with little connection to white Southerners who once kept Democrats in power in the region.

That's left the South a starker, more sharply divided microcosm of the demographic dynamics at play across the country.

Republican presidential candidates are fighting for support from a mostly white electorate, including many voters who feel alienated by sweeping economic and cultural changes.

Democrats will depend on growing minority populations and voters — white and nonwhite — clustered in heavily populated urban areas.

In the upcoming Southern primaries, that means Hillary Clinton could sweep the region, but with Democratic electorates that have much larger proportions of African-Americans than those that propelled her husband's successful 1992 campaign.

The changes have given Donald Trump, hardly a conservative by traditional definitions, an unexpected foothold with voters who feel both emboldened in the South and left behind by their party's leaders in Washington.

Clinton's big win in South Carolina sets her up for a potential Super Tuesday triumph over her rival, Vermont Senator Bernie Sanders. Although she lost to Sanders in New Hampshire and only beat him by narrow margins in Iowa and Nevada, many polls suggest Clinton could win most or even all of the Democratic primaries being held on Tuesday.

Pundits believe Sanders will try to stay close to Clinton in the South while focusing most of his attention on states in the Midwest and Northeast, including the senator's home state of Vermont.

With files from CBC News