Donald Trump rolled to a win in South Carolina's Republican primary on Saturday as voters seething about Washington and politicians lifted the billionaire businessman to his second straight victory in the presidential race.

The two freshmen senators — Ted Cruz of Texas and Marco Rubio of Florida — were battling for second place, which would give them bragging rights but might not get them any delegates in the march to the nomination.

The outcome could also have serious implications for more establishment-friendly candidates who are hoping for strong finishes to stave off questions about their viability.

Exit polls showed four in 10 voters angry about how Washington is working, and more than half saying they felt betrayed by politicians in the Republican Party.

"I don't like politicians," said Jim Jaruszewicz, a 37-year-old radiology technician who voted for Trump. "I don't trust politicians."

The survey also found that three-quarters of voters supported a temporary ban on Muslims who are not U.S. citizens from entering the country, one of Trump's policies.

Trump appeared confident as he's travelled the state this week, holding rallies and town halls that have drawn thousands.

"I actually think I know your state now better than you do. I have been all over the place for the last four days. I know every blade of grass I've flown over from here to there," he told a rally crowd in Sumter as he implored his supporters to get out and vote.

While the billionaire businessman scored a decisive win in New Hampshire, his second-place finish in Iowa to Cruz illustrated gaps in his less-than-robust ground operation, and questions remain about the extent to which he can translate leads in preference polls and large rally crowds into votes.

Trump's win could answer some of those questions, adding momentum going into the collection of Southern states that will vote March 1, giving him the chance to build an even bigger lead in the delegate count that will determine the nomination.

The election followed days of hostility between the campaigns and their allies at events and in television ads, automatic calls and mailers that have been flooding voters' mailboxes.

Trump added to the drama, spending the week threatening to sue Cruz, accusing former President George W. Bush of lying and sparring with Pope Francis over immigration.

At his final election-eve rally Friday night in North Charleston, Trump told the widely discredited story of Gen. John Pershing, who was said to have halted Muslim attacks in the Philippines in the early 1900s by shooting the rebels with bullets dipped in pigs' blood.

The outcome will also have high stakes for Trump's rivals, who are hoping to halt his momentum and establish themselves as the best-positioned alternatives to his unorthodox candidacy. Cruz and Rubio were battling for second place.

Former Florida Gov. Jeb Bush's finish below the top three could raise serious new questions about his campaign and increase pressure on him to drop out. Bush has deep family ties in the state and campaigned alongside his mother, the former first lady, and his brother, former President George W. Bush.

The exit polling of voters was conducted for The Associated Press and the television networks by Edison Research.