Nikki Haley under attack and more Republican debate takeaways

The fourth Republican debate featured a much-diminished field, but the night fell into a familiar pattern: rivals firing attacks at an ascendant candidate, a longshot candidate grasping at insults, and a palpable absence of the actual frontrunner, Donald Trump.

Polling shows the former president remains far ahead of any of the candidates onstage despite skipping each debate. His political action committee did not mince words and called the event a "race for second place".

The debate took on new urgency as the candidates - former UN Ambassador Nikki Haley, former New Jersey Gov Chris Christie, Florida Gov Ron DeSantis, and entrepreneur Vivek Ramaswamy - only have mere weeks to cobble together support before the first contest in Iowa.

Each candidate used their precious time on the debate stage differently.

Mr Christie pressed his colleagues to denounce Mr Trump, Ms Haley flaunted her foreign policy credentials, Mr DeSantis emphasised his culture war success in Florida and Mr Ramaswamy embraced conspiracy. At several points, personal insults flew between the candidates.

Here are the most important takeaways from Wednesday's debate.

As in each previous debate, the candidates all had a primary target. Tonight's was Nikki Haley.

The former South Carolina governor and UN Ambassador has seen a surge in momentum, though she still places third in most polls and trails far behind Mr Trump.

But her recent success earned more than a few pointed attacks.

Mr DeSantis accused her of changing her position on transgender youth treatment, which he opposes. Mr Ramaswamy attacked her for joining the Boeing board of directors after departing government service. He further claimed she backed progressive business principles that have faced conservative criticism.

"You are corrupt," he declared bluntly.

Ms Haley appeared unfazed.

"I love all the attention fellas, thank you for that," she quipped.

In her closing pitch, Ms Haley cited polls to emphasise she was the only candidate in the race who could beat Joe Biden in the general election.

Mr Christie appeared to find his greatest success on the debate stage in his return to his faithful role as an attack dog focused squarely on Mr Trump.

He seized on the former president's recent quip that he would only be dictator for "day one" of his presidency. The former New Jersey governor warned Republicans and said Mr Trump was a "dictator" and "bully" focused entirely on exacting retribution.

Mr Christie also shared his disappointment that his fellow candidates have shied away from harshly criticising Mr Trump. Their silence makes "it seem like his conduct is acceptable", he said.

The only other candidate who criticised Mr Trump on stage was Mr DeSantis, who was pushed by the debate moderators to speak on the topic. The governor, who is 45, argued Mr Trump, 77, was too old to serve as president and had not fulfilled his key 2016 campaign promises on immigration.

"I think we need to have somebody younger. I think when you get up to 80, I don't think it's a job for that," Mr DeSantis said.

Mr Ramaswamy promised reporters he would bring his "brutally frank" candour to the final debate. Most did not anticipate that meant he would fully embrace conspiracy theories and fling even more insults on live television.

Mr Ramaswamy ticked off a laundry list of conspiracies in an apparent bid at chumming the waters for far-right voters. He applauded himself for being the only one at the debate willing to say that the 6 January 2021 riot at the US Capitol was an inside job. He then claimed that the American government lied about 9/11 and that the 2020 election was stolen by the tech industry.

The American pharmaceutical entrepreneur also endorsed the great replacement theory, a racist conspiracy theory that claims there is a secret plan to replace white people in Europe and the US through mass migration. Civil rights groups say the theory promotes white supremacy.

Mr Ramaswamy has not feared courting controversy or lashing out at his fellow candidates, which in turn has earned their ire in past debates.

This time he accused Ms Haley of corruption and Mr Christie of being a fascist.

Mr Christie responded by calling Mr Ramaswamy the "most obnoxious blowhard in America" and telling him to "shut up for a little while".

After calling the entrepreneur "scum" at the last debate, Ms Haley took a different approach. When given the chance to respond to Mr Ramaswamy, Ms Haley said his attack "was not worth my time to respond to".