Trump secures decisive victory in South Carolina Republican primary

Donald Trump won an overwhelming victory over his rival Nikki Haley on Saturday in South Carolina's Republican primary, continuing his march to the nomination and a White House rematch with Joe Biden in November.

Mr Trump completed a sweep of the first four major nominating contests, converting a year of blockbuster polls into a likely insurmountable lead going into the “Super Tuesday” 15-state voting bonanza in 10 days.

Ms Haley had vowed to fight on regardless of the outcome but Mr Trump, seeking to move quickly from the primary to the general election, didn't mention her once during a victory speech in which he turned his fire on Mr Biden.

“We're going to be up here on November 5 and we're going to look at Joe Biden – we're going to look him right in the eye, he's destroying our country – and we're going to say, Joe, you're fired. Get out,” Mr Trump said to cheers at his victory party in state capital Columbia.

Ms Haley has repeatedly questioned the 77-year-old former president's mental fitness and warned another Trump presidency would bring “chaos”, but her efforts appeared to do little to damage his standing among Republicans.

Mr Biden reacted to the South Carolina result by warning Americans of “the threat Donald Trump poses to our future as Americans grapple with the damage he left behind”.

Meanwhile Ms Haley reminded supporters as she congratulated Mr Trump in her concession speech that she had already vowed to fight on, regardless of the outcome.

“I'm a woman of my word. I'm not giving up this fight when a majority of Americans disapprove of both Donald Trump and Joe Biden,” she said.

The margin of victory was not immediately clear but US networks felt able to call the race within seconds of the polls closing, suggesting that there was little doubt over the outcome.

Ms Haley, a popular governor of South Carolina in the 2010s and the only woman to have entered the Republican contest, was looking to outperform expectations in her own backyard and ride into Super Tuesday with wind in her sails.

But she was never able to compete in a battleground that preferred Mr Trump's brand of right-wing “America first” populism and personal grievance over the four criminal indictments and multiple civil lawsuits he faces.

Mr Trump's campaign co-manager Chris LaCivita told Reuters that a series of high-profile endorsements of his campaign played a critical role in defeating Ms Haley in her home state.

Mr Trump secured the endorsements of a range of influential Republicans in South Carolina, including officials, mayors and sheriffs.

These included South Carolina state governor Henry McMaster, former ambassador to Switzerland Ed McMullen, and Justin Evans, who previously ran Ms Haley's 2010 campaign for governor of South Carolina.

"We were facing a two-term governor. That necessitated a show of force. We needed endorsements to stop donors and voters taking a look at Nikki," a senior Trump campaign adviser told Reuters on condition of anonymity.

In January, Mr Trump's campaign received a boost with the endorsement of Tim Scott, one of South Carolina's two Senators. Mr Scott, who had initially challenged Mr Trump in the presidential race but dropped out in November, is seen as an influential voice in the state and his endorsement a major prize.

His endorsement has added value because it was Ms Haley who had appointed him to his Senate seat in 2013 when she was governor.

Mr LaCivita also said Mr Trump's campaign had utilised the data of thousands of voters who had attended his rallies.

Before his victory in South Carolina, Mr Trump had already won Iowa by 30 points and New Hampshire by 10, while a dispute in Nevada led to the real estate tycoon running unopposed in the first official contest in the western US.