The latest Republican debate - the last before the people of Iowa actually start casting votes - covered a lot of ground. It went into policy and positions to a greater degree than any of the previous six.

And that was perhaps because Donald Trump wasn't there.

The Republican frontrunner has dominated the previous gatherings with his personality, overshadowed the others on the stage with his sound bites and his attacks. But this was much more nuanced, more inquisitorial and perhaps because of that, Donald Trump was the biggest winner.

Annoyed at the hosts, the Fox News Channel and in particular at one of the moderators, the billionaire businessman packed up his big poll lead in Iowa and held his own event across town.

Fox had its debate. Every other news channel in America covered Trump. With less than 24 hours’ notice, he packed a 700 capacity hall, with many more wanting tickets.

He never had to face the tough questions on his changing positions. He never had to answer for his support of the leading Democrat Hillary Clinton. He wasn’t fact checked on some of his previous comments. Instead he got to speak uninterrupted and unchallenged for thirty minutes.

Lacking ground game

It is a gamble. The voters of Iowa may feel insulted he skipped out. But what may cost him more come Monday’s caucuses is the lack of organisation on the ground. To win in Iowa you need supporters, organisers and promotors across the state. Other candidates have much stronger ground games. Donald Trump hasn’t given it too much attention.

With Trump off the stage it gave the others more time and space to expand their ideas. The biggest beneficiary was Jeb Bush. The former Florida governor has been bullied and belittled by Trump in previous debates. Now he seemed more in control. He handled questions on Islamophobia and immigration with self-assurance and turned in his best performance in a format in which he clearly struggles. He's building in momentum in New Hampshire, but as the race tightens he might find himself forced to back another candidate to stop his nemesis.

With no Trump, Ted Cruz became the focus of attack. Sitting second in the polls, the Texas senator had the chance to shine and grab the moment. He didn’t but he didn’t hurt himself either. He was brave to confront the popular and long serving Republican Governor in Iowa who insisted Cruz must be defeated. And he was strong when confronted on seemingly moving positions on immigration. But his attempts at humour were weak. When he said he'd walk off the stage if he got another nasty question (a sideswipe at Trump) it actually came across as a petulant threat.

He was at the centre of the sharpest exchange of the night with Florida senator, Marco Rubio on immigration. Rubio got angry that his position was portrayed more as revolving than evolving. Rubio is a lot of what the Republicans were looking for; young, engaging, smart and Latino. But he hasn't made the impact many predicted. He is still best placed to be the 'establishment' candidate to tackle the outsiders of Trump and Cruz and he seized most air time with his aggressive attacks.

The surprise of the night was Rand Paul. The Kentucky senator was restored to the main stage and went on the attack, hitting Cruz on immigration and Rubio on foreign policy. He gave a nuanced answer on criminal justice. His supporters in the hall were loud - but his performance is less likely to give him a lift than tear down support for those he hit.

New Jersey Governor, Chris Christie was the one who seemed most often to attack Democratic front runner Hillary Clinton. He paints himself as plain spoken Washington outsider. And while he won't be in the top three in Iowa his numbers are growing in New Hampshire. Yet his best chance of the nomination is if Rubio runs into trouble.

Also on the stage were Ohio Governor John Kasich and neurosurgeon Ben Carson. While Kasich has never been high in the polls, Carson is on a steady trajectory down and nothing happened in the debate to suggest either of those positions will change.

It'll be interesting to see the viewing figures for the debate. The Trump experience has pulled in record rating for the US networks showing them.

He's been a big winner for them. And even though he wasn't there - he was the winner again in Des Moines.