A smaller field, a brighter spotlight and some of the angriest exchanges of this long nominating process. The latest Republican Presidential debate in South Carolina showed as that as this race tightens, it is going to get nasty.

There were several noteworthy exchanges - mainly between Donald Trump and Ted Cruz .

Alan Fisher looks back at the night.

Jeb Bush: The former Florida Governor had Donald Trump telling him to his face he was ‘weak’. He argued passionately again Trump’s plan to temporarily ban all Muslims from entering the US. But the reality is Trump has found an issue which resonates with the Republican party. The other candidates offered watered down versions of the Trump plan. He had perhaps his best night, with clear answers on the economy and immigration but it may be too late.

Ben Carson: The former neurosurgeon started with a joke about his reputation for being sleepy and laid back - and did nothing to dispel that. He struggles on foreign policy and national security. His best moment of the night was when he jumped into an argument in response to another candidate to grab some time. It got a big laugh but voters are looking for more.

Chris Christie: Took on Rubio’s claim that he was too liberal and skillfully beat off the attack. But he does keep fact checkers busy. Says he did not tighten gun laws as Governor in New Jersey. He did. He says he did not support the appointment of a liberal Justice to the Supreme Court. He did. His comment to President Obama that 'we’re going to kick your rear end out of the White House’ played well in the hall but would not have endeared him to many Americans who may disagree with the President, but respect the office.

Ted Cruz: Took the first question on the economy and turned it into an attack on Barack Obama’s foreign policy. Neatly waved off Trump’s attack that he isn’t qualified to run for President because he was born in Canada and awkward questions about the financing of his Senate campaign. But the best debater on stage looked slightly rattled when his attack on Trump’s 'New York values', code for being too liberal, was turned by Trump into an insult of the city’s recovery from the 9/11 attacks. And when Marco Rubio claimed he had flip flopped on several key issues. A problem for the Texas senator may be his tax plan and that may come back to haunt him. Still had a very good night.

John Kasich: The Ohio governor tried to stay about the squabbling and the arguments and seemed less of the angry old man he has been in the previous two debates. He tried to focus on the economy. He tries to steer his party to more central ground where he believes the presidential election will be won. But he won’t be running for President if he can’t win the Republican nomination. He had a solid performance which was lost in the noise.

Marco Rubio: The Florida senator has an immigration problem. In 2013 he was one of a 'gang of eight' senators who tried to streamline immigration laws which would give a path to citizenship to a large numbers of undocumented workers in the US. Now he says his position’s changed because of threats to the country from a 'radical jihadist group' and immigration is a huge security issue. Ted Cruz attacked him on that. Rubio aggressively rounded on Cruz to provide his best moment of the night. But the reality is mainstream Republican voters don’t like the position he had - and his own Hispanic base do not like where he is now. He has to find some way to neutralize the issue.

Donald Trump: The billionaire businessman has become a better debater as this process has gone on. He seemed to struggle under Cruz’s response to his 'birther’ attack but quickly regained his feet, and his response on New York brought cheers. For the first time, there were significant boos in the hall to some of Trump’s answers. And it’s clear he doesn’t quite have a full grasp of some complicated issues resorting instead to soundbites and tried and tested lines he knows will play well with the base. If he fails to win Iowa, and he’s behind in the polls, he may see support which has been strong and consistent since the summer leak away to other candidates.

Where the candidates concentrate their attacks give an idea of who they see as a threat. No one attacked Kasich or Ben Carson. Rubio went after Christie and that was returned. Both are what’s consider the 'Establishment' wing of the party. He also hammered Cruz when he could. Cruz won’t go full out against Trump believing his supporters will move to him if the businessman drops out, but he’s happy to hammer Rubio.

Now the candidates head to Iowa. Another debate, another battle and the first real test from the voters.

Source: Al Jazeera