Charleston (United States) (AFP) - Former US president Donald Trump eased to victory in South Carolina, dismissing Nikki Haley and closing in on the Republican nomination as he seeks a second term in the White House.

Here are five takeaways from Saturday night:

The speed of victory

Trump's opponents griped bitterly that the media had jumped the gun when his victory in Iowa was announced just half an hour after polls closed in the first contest of the primary season in January.

Those howls of complaint were largely absent when the first projections for South Carolina came in within seconds on Saturday.

The former president had already won all four previous nominating contests and opinion polls gave him almost double Haley's support -- making an early call almost inevitable rather than a potential controversy.

Some experts were reckoning ahead of the vote that Haley could count defeat by 15 points or less as a decent night, although the margin looked like it was going to be closer to 20 percent with most of the ballots tallied.

Whatever the final score, it was another big "L" for Haley -- and a reminder that she has yet to pose a credible threat to the former president in any state.

No home advantage for Haley

In a primary contest that looks like it could be a rocky ride for Haley in every corner of America, her home turf of South Carolina was seen by her more optimistic backers as a port in a storm.

The 52-year-old Ronald Reagan-style conservative was a popular governor, known as a cost-cutting advocate of small government and even smaller tax bills.

It was a manifesto that got her elected for two terms from 2011 to 2017.

But her defeat was never so much about Haley herself as the deep loyalty South Carolinians have for Trump -- and the deference of a political establishment that got fully behind the candidate once seen as an outsider.

Both of the state's US senators and five of the six-strong delegation it sends to the House of Representatives endorsed Trump. 

He was also backed by 25 state representatives to Haley's four -- not to mention South Carolina's incumbent governor, Henry McMaster, and three of his top officials.

Trump's appeal was obvious in opinion polling that showed him up to 30 points in the run-up to Saturday's vote.

But anyone studying his presidential election history in the Palmetto State -- wins in 2020 and 2016 with 55 percent and 54 percent respectively -- would have been able to read the runes before a ballot was cast on Saturday.

Trump moves on...

With South Carolina now in his column, the former president has covered most of the compass, having notched victories in the Northeast, Midwest, South and West.

Trump's frustration at Haley continuing to fight was obvious when he turned his victory speech in New Hampshire last month into a bitter rant against his sole remaining challenger.

In South Carolina, he cut an altogether calmer, more focused figure, neglecting to mention Haley at all as he made clear that he had moved past the primary campaign mentally, with his sights set on November.

Expect Trump's campaigning in the coming weeks to follow a similar pattern -- concentrating on the catastrophe he claims President Joe Biden has been for the United States instead of dwelling on his polling numbers against Haley.

Haley's defiant promise to fight on after Saturday's loss was hardly a surprise.

Her official position -- made clear in the days before the primary -- was that she would be all-in until at least "Super Tuesday" on March 5, when 16 states and territories weigh in on the Republican presidential nomination.

She had also addressed supporters in California and Texas, and her aides told reporters the campaign was committing to a "seven-figure" national cable and digital ad buy in the Super Tuesday states.

"South Carolina has spoken -- we're the fourth state to do so," she told supporters at her election night watch party.

"In the next 10 days, another 21 states and territories will speak. They have the right to a real choice, not a Soviet-style election with only one candidate."