Former president Donald Trump is looking to win his fourth straight primary state on Saturday over Nikki Haley in South Carolina, aiming to hand a home-state embarrassment to his last remaining major rival for the Republican nomination.

Mr Trump went into the primary with a huge polling lead and the backing of the state’s top Republicans, including senator Tim Scott, a former rival in the race.

Ms Haley, who served as UN ambassador under Mr Trump, has spent weeks criss-crossing the state that twice elected her governor warning that the dominant front-runner, who is 77 and faces four indictments, is too old and distracted to be president again.

In all but one primary since 1980, the Republican winner in South Carolina has gone on to be the party’s nominee. But Ms Haley has repeatedly vowed to carry on if she loses her home state, even as Mr Trump positions himself for a likely general election rematch against US President Joe Biden.

Mr Trump’s backers, including those who previously supported Ms Haley during her time as governor, seemed confident that the former president would have a solid victory on Saturday.

“I did support her when she was governor. She’s done some good things,” Davis Paul, 36, said as he waited for Mr Trump at a recent rally in Conway. “But I just don’t think she’s ready to tackle a candidate like Trump. I don’t think many people can.”

Mr Trump has swept into the state for a handful of large rallies in between fundraisers and events in other states, including Michigan, which holds its Republican primary on Tuesday.

He has drawn much larger crowds and campaigned with governor Henry McMaster, who succeeded Ms Haley, and Mr Scott, who was elevated to the Senate by Ms Haley.

Speaking on Friday, Mr Trump accused Ms Haley of staying in the race to hurt him at the behest of Democratic donors.

“All she’s trying to do is inflict pain on us so they can win in November,” he said. “We’re not going to let that happen.”

Ms Haley has made an indirect appeal to Democrats who in large numbers sat out their own presidential primary earlier this month, adding into her stump speech a line that “anybody can vote in this primary as long as they didn’t vote in the February 3 Democrat primary”.

Some of those voters have been showing up at her events, saying that although they planned to vote for Mr Biden in the general election, they planned to cross over to the Republican primary on Saturday as a way to oppose Mr Trump now.