One of the first signs that the presidential campaign had arrived in the wild and woolly political state of South Carolina came when Senator Lindsey Graham introduced his favoured candidate, Jeb Bush, and issued a warning: "If you're not ready to play, don't come to South Carolina."

A state known for its nasty political brawls is about to host an epic one, pitting a foul-mouthed celebrity billionaire against a band of senators and governors scrapping to challenge him.

The Republican presidential candidates - minus Chris Christie and Carly Fiorina, who dropped out of the race - arrived ready for 10 days of combat that could bring clarity to what has been a muddy nomination contest.

Since Wednesday's New Hampshire primary failed to deliver much certainty, the Palmetto State's GOP primary on February 21 could determine the future for three candidates vying to become the GOP establishment's consensus alternative to frontrunner Donald Trump and Senator Ted Cruz of Texas.

Advertisement

The attacks began early. Aboard a chartered jet en route to Spartanburg, Senator Marco Rubio bashed Bush, his one-time mentor, for lacking foreign-policy experience and Trump for not sharing policy specifics. Later in the day, he talked up his opposition to the Common Core education standards, an implicit dig at Bush and Ohio Governor John Kasich, who are proponents.

Bush and his aides hit Kasich for expanding Medicaid under President Barack Obama's healthcare law and for supporting defence cuts. "He led the charge to expand Medicaid and is quite proud of that," said Bush, a former Florida Governor. "I wouldn't be proud of that, to be honest with you." Bush also hit Trump, calling him a "phenomenal entertainer" who lacks the temperament to be president.

Donald Trump. Photo / AP
Donald Trump. Photo / AP
Republican presidential candidate, Sen. Marco Rubio. Photo / AP
Republican presidential candidate, Sen. Marco Rubio. Photo / AP

Katon Dawson, a former state GOP chairman, explained what makes the South Carolina primary unique. "People in Iowa expect the candidate to trudge through the snow, do small meetings in diners," he said. "In New Hampshire, they expect a candidate to come to their living room, sit on the sofa, have some coffee. In South Carolina, 700,000 people want to see how you take a punch."

Trump sits in the pole position in the state, where his anti-immigration, outsider crusade has found deep support. Top South Carolina Republicans see Trump as the one to beat, noting that the electorate historically votes based on values and emotion.

Trump rallied a few thousand supporters at the Clemson University livestock arena in Pendleton, where he went after only one opponent: Bush. He called him "low energy" and a "stiff" who is controlled by his donors. "The last thing we need is another Bush," Trump said as the crowd cheered.

Trump has about a dozen campaign staffers and four offices in the state, along with three RVs that function as mobile offices in rural areas. But it is unclear whether they can persuade the thousands of people who pack his rallies to cast ballots for him in a primary expected to draw exponentially more voters than the Iowa or New Hampshire contests.

The most consequential moment may be Sunday's debate on CBS, where Trump could come under intense fire from Cruz and Bush and where Rubio will seek redemption from a disastrous debate that wounded him in New Hampshire. In 2012, Newt Gingrich's electric performances in two debates the week before the primary lifted him from a hobbling third place in the polls to a decisive victory over Mitt Romney.

What's next?

Democrats

Today: Debate in Milwaukee
February 21: Nevada caucuses
February 28: South Carolina primary

Republicans

Sunday: Debate in Greenville
February 21: South Carolina primary
February 24: Nevada caucuses