(CNN) Hillary Clinton will win the Nevada Democratic caucuses, CNN projects, a crucial victory that could ease concerns about her ability to secure the party's nomination.

The win provides a jolt of momentum to the former secretary of state as she heads into the February 27 South Carolina Democratic primary and Super Tuesday on March 1.

Clinton faced a surprisingly spirited challenge here from Democratic rival Bernie Sanders. The two were in a virtual dead heat in recent days. A win by Sanders, who trounced Clinton in the New Hampshire primary, would have dealt Clinton a dramatic setback.

Clinton relied on strong turnout from Latino voters to hold Sanders at bay. Her surrogates fanned out across the Silver State this week, attempting to portray her as the more trustworthy candidate for Latinos.

Meanwhile in South Carolina, Republican voters are putting their strong record of anointing GOP nominees on the line. Polls there close at 7 p.m. ET where 50 of the 1,237 delegates needed to win the Republican nomination are at stake.

Donald Trump goes into the vote as the front-runner after a frenzied final week of campaigning that saw the billionaire real-estate mogul wage a rhetorical war with Pope Francis and several candidates bluntly accuse their rivals of peddling outright lies.

There was a furor over doctored pictures of Florida Sen. Marco Rubio in a Photoshopped handshake with President Barack Obama and a shouting match -- again initiated by Trump's willingness to slay sacred cows -- over who was to blame for 9/11.

And Trump again managed to draw controversy in his final rally before the primary Friday night, when he told an apocryphal story of Gen. John Pershing, who purportedly dipped bullets in pigs' blood to execute Muslim prisoners a century ago in an effort to deter Islamic terrorism. Rubio, speaking to NBC's "Today" show on Saturday, called the tale "bizarre" and said "that's not what the United States is all about."

Former President George W. Bush himself was back on the trail for the first time since leaving the White House, showing that his campaign skills are as polished as ever. But the 43rd president may not have done enough to rescue his brother Jeb, who is struggling to gain traction.

The latest CNN Poll of Polls on Friday showed Trump potentially on the verge of another huge victory to back up his thumping win in New Hampshire last week.

The businessman led with 34% support, ahead of Texas Sen. Ted Cruz at 20% and Rubio at 15%.Bush was fourth with 11%, ahead of retired neurosurgeon Ben Carson at 8%.

One point back was Ohio Gov. John Kasich. He might get a pass in South Carolina, however, because his more-moderate conservative profile is a weaker fit in the Palmetto State than in New Hampshire, where he came in second last week.

A Trump victory in South Carolina on Saturday would send new shockwaves through the Republican establishment and possibly augur another strong showing for the front-runner in Southern states with a similar ideological profile on Super Tuesday, March 1.

Despite an aberration in 2012, when the state's Republican voters went for Newt Gingrich, the South Carolina primary has historically been a barometer of party opinion, going for the eventual nominee in every other presidential primary since 1980.

It's also a good approximation of the party as a whole. It has a mixture of conservative and evangelical voters, particularly in the northwest of the state, and an influential bloc of retired military veterans who hanker for a tough message on national security, with more moderate Republicans on the Atlantic coast where cities have swelled with migrants from northern states.

The race is another test of whether the outspoken former reality star can defy political logic after firing off a string of political assaults, notably accusing George W. Bush of not doing enough to thwart the September 11 attacks and of lying America into the Iraq war. Bush remains popular in South Carolina, so while Trump's attacks could endear him to his anti-establishment base, they also could backfire.

But Trump appears confident that his lead will hold up on Saturday, having proven that his campaign, despite doubts about his ground game, was able to turn poll numbers into significant amounts of votes in New Hampshire.

Trump -- who has taken aim at establishment figures throughout his campaign -- also found himself at odds with the head of the Roman Catholic Church on Thursday, when Pope Francis warned that his talk of building walls to keep out immigrants was hardly Christian.

The spat may have helped Trump, given the lack of Roman Catholics in South Carolina -- 7% according to the beliefnet website. Some evangelicals, meanwhile, mistrust Francis' comparatively progressive views on certain social and economic questions. And the exchange allowed the billionaire to once again dominate the media as he restated a hardline position on illegal immigration popular among many conservatives.

Behind Trump, a furious battle appears to be raging for second place between a pair of Cuban-American senators, Rubio and Cruz, who have engaged in a series of angry exchanges that reflect the intensity of the South Carolina race.

Rubio is looking for a strong performance on Saturday to validate the comeback story he has been building after slumping to fifth place in New Hampshire. Just days earlier he was pummeled in a debate by New Jersey Gov. Chris Christie, who has since dropped out of the race.

Rubio secured the endorsement of South Carolina Gov. Nikki Haley and South Carolina Sen. Tim Scott, both rising stars in the GOP, and has hired a group of political consultants who learned their trade in the Palmetto State so must deal with rising expectations for a competitive showing on Saturday.

A good result for Cruz, meanwhile, would lend credence to a theory of the campaign that rests on a string of strong performances in very conservative and evangelical Southern states.

In their latest spat, Rubio expressed outrage at a doctored photo distributed by Cruz's campaign purportedly showing him shaking hands with Obama.

But Cruz hit back by saying Rubio was just like Trump and had a thin skin when it was his turn to absorb an attack. "They start screaming, 'liar, liar, liar,'" Cruz said.

Former Florida Gov. Bush, meanwhile, is trying to use South Carolina -- a stronghold for the presidential campaigns of his brother and father -- to launch a comeback after bad showings in Iowa and New Hampshire.

But he has struggled for traction and if he fails to beat Rubio on Saturday, he will face questions about the rationale for continuing a campaign that is currently helping to fracture the establishment wing of the party and leaving an opening for Trump to build momentum.