Iowa caucus: Nikki Haley's campaign could be over in a month after ...

“My guess is that this race will be over before Super Tuesday [in March] because Trump will bury Haley in South Carolina [in February], which is rough given it is her home state,” Cook said.

Haley vowed to keep fighting for the nomination, as all three candidates head to New Hampshire next week for another round of Republican voting. She told supporters America “deserves better” than a rematch between Trump and US President Joe Biden.

“At one point in this campaign there were 14 of us running. I was at 2 per cent in the polls,” Haley told a crowd of supporters. “When you look at how we’re doing, in New Hampshire, in South Carolina and beyond, I can safely say tonight Iowa made this Republican primary a two-person race.”

Part of Haley’s rise while campaigning in deep-red Iowa could be put down to her liberal views on everything from abortion to immigration and trade. Her fund-raising has also been arguably more successful than Trump and DeSantis, but that has also been part of her undoing.

She received funding from billionaire liberal donors such as the Koch family, as well as LinkedIn founder and Democrat supporter Reid Hoffman.

Republican voters in Iowa said they were suspicious of her support, seemingly from Democrats. “I didn’t vote for Nikki Haley because she is a Democrat. She is funded by the Democrats,” Des Moines resident Carrie Phelps said.

Another Iowan woman, Rachael, said: “She has been funded by people who are questionable. Trump doesn’t have to be funded by anyone, has no strings attached to him.”

Carrie Phelps said she did not vote for Nikki Haley because she thought she was aligned with the Democrats.  Matthew Cranston

Metals magnate and Republican donor Andy Sabin told reporters he was proceeding with a large fundraiser for Haley on January 30 “where we’re raising a tremendous amount of money, and believe it or not a number of it is coming from Democrats”.

Haley-aligned political committees spent $US4 million ($6 million) in advertisements in the past week, up from $3.7 million previously, and all of them targeted DeSantis.

Some experts warned against writing off Haley in independent-minded New Hampshire next week, saying support was still strong, especially among college-educated Republicans. They pointed to the fact Trump came second to Ted Cruz in the 2016 Iowa contest, before bouncing back to not only win the nomination but the eventual presidency.

But others said the result was not enough to build the momentum she needed to really take on Trump’s impenetrable base.

Kyle Kondik, managing editor of election forecaster Sabato’s Crystal Ball, said Haley had to not only beat rival DeSantis, but also capture more than 20 per cent of the vote for herself, and make sure Trump scored less than 50 per cent, to really establish any sort of lasting momentum.

“But even then, none of it matters if Haley doesn’t win New Hampshire, and that needs to be a precursor to her winning South Carolina, which is a harder state for her than New Hampshire despite her being from South Carolina,” Kondik said.

On the campaign trail, Haley has been touting her ability to beat Biden if she were to win the Republican nomination. But of the last five national polls between her and the Democratic president, she has lost to him in all but one. In a match-up between Trump and Biden, on the other hand, Trump wins two, ties two and loses one.