Republican presidential debate: How Donald Trump's performance may stall campaign

Whether any one candidate "won"the first U.S.Republican presidential debate may not have been nearlyasimportant as the overallperformance of front-runner Donald Trump.

And on that front, the billionaire businessmanmay have caused his campaignsome damage.

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"The real storyis the collapse of Trump in this debate," conservative columnist Charles Krauthammer told Fox News' Megyn Kelly, one of themoderators of the debate.

"That was supposed to be hisnight, the expectationswere particularlyhigh ...I thoughthe hada flat night and one that I'm notsure he's goingto like."

Florida Senator Marco Rubiocertainly had a solidnight,whileformer Arkansas governor Mike Huckabee, Texas Senator Ted Cruz, New Jersey Gov.Chris Christie and Ohio Gov.John Kasich were allstrong performers.

Two of the other top-tier candidates, formerFlorida governor Jeb Bush and Wisconsin Gov.Scott Walker made no mistakes, but seemed to play it safe, deliveringsomewhat underwhelming performances.

In fact the night, in terms of winners, may have belonged toCarly Fiorina. The California businesswomanwas the clear stand-outamong pundits in the so-called 'kids-table' debate that took place hours before the prime-time contest forcandidates with low polling numbers.

But the night was really all about Trump, and how he was able to handlehimself.

'Damaged him considerably'

Heimmediately earnedthe ire of the crowd, and likely manyRepublican supporters in general, when he would not commit to supporting the party's eventual nominee and would not rule out running as a third-party candidate.Many believe athird-party run would only split the Republican vote and ensure a Democratic victory.

"That,I think, damaged him considerably," said Republicanstrategist Ron Bonjean. "I think his numbers will slip because of that. It just didn't show loyalty to the Republicanparty."

Aaron Kall, director of debate at the University of Michigan,said that while Trumpdid eventually recover,it was a horrible start.

You couldn't imagine there being a scenario that started out worse for the front-runner.- Aaron Kall, University of Michigan

"I think if you would have tuned into the first five minutes ofthe debate, you would have said he blew it. You couldn'timagine there being a scenariothat started out worsefor the front-runner," he said.

As forTrump's exchange withFox NewsmoderatorKelly over the issue of derogatory comments he's made against women, it's hard to say what impact that will have on his campaign.

Kellyrecited a list of nasty insults Trump had hurled atwomen, terms thatincluded "fat pigs, dogs,slobs and disgusting animals."Trump defended his actions, joking thatthose insults weredirectedat actress and comedianRosie O'Donnell (the two had a tiff years back).But he also said many of those comments should not be taken so seriouslyand that people need to stop being so politicallycorrect.

His conservative credentials were also tested.He was asked about his pastsupport for Canada's one-payer health-care system, a policy strongly opposed byRepublicans who have pledged to overturnObamacare. Trumpresponded that the policyworks for Canadians, and also works in Scotland, but that he favours privatized health care in the U.S.

Hewas also questionedabout his past financial support for Democratic candidates, including then New York senatorHillary Clinton, and asked what he got back in return for that support. Trump shot back that he got Clinton to go to his wedding.

"I thought Trump lost this debate because he's sitting on top the mountain and nowpeoplewill have the chance to pull the curtains back and they can see he's not a reliable conservative," Bonjean said.

'Drop in the polls'

"I thinkhe will probably drop in thepolls now because he was forced to talk in more than soundbites. Some of thethings he said werehead scratching."

Part of the problem for Trump may have been the debate format itself, which reined in the free-wheeling candidate.

"Here's what killed him that tight controlled setting," said Republican strategist Ford O'Connell. "Trump is great if you let Trump goon his own. Trump has to figure out to make the same points he makes when he is basically unfiltered, in a tight controlled debate setting."

"When somebody can't control themselves upthere andand continues to challenge questions, it doesn't leave you with the impression that you can sit in the Oval Office."