US:Republican presidential candidates stopped attacking Democratic frontrunner Hillary Clinton and turned their fire on one another in a debate on Wednesday that saw the sharpest exchanges of the campaign so far, notably on illegal immigration.
The most bruising clashes were between former New York mayor Rudy Giuliani, who leads in national polls, and former Massachusetts governor Mitt Romney, who is ahead in the early-voting states of Iowa and New Hampshire.
The debate's biggest winner, however, was former Arkansas governor Mike Huckabee, a dark-horse candidate who has risen dramatically in Iowa polls in recent weeks and who gave a witty, poised performance throughout the debate in the Florida city of St Petersburg.
Mr Romney said Mr Giuliani had a record of indulgence towards illegal immigrants, pointing to the fact that the former mayor declared New York a "sanctuary city", allowing undocumented immigrants to use public schools and emergency medical facilities and to report crimes without fear of arrest and deportation.
Mr Giuliani shot back that Massachusetts had six sanctuary cities when Mr Romney was governor.
"There was even a sanctuary mansion. At his own home, illegal immigrants were being employed, not being turned in to anybody or by anyone. And then when he deputised the police, he did it two weeks before he was going to leave office, and they never even seemed to catch the illegal immigrants that were working at his mansion. So I would say he had sanctuary mansion, not just sanctuary city," he said.
Mr Romney also accused Mr Huckabee of being soft on illegal immigrants by allowing their children to win college scholarships in Arkansas.
"In all due respect, we are a better country than to punish children for what their parents did. We're a better country than that," Mr Huckabee replied to applause.
A former Baptist minister who wrote a health and exercise book called Quit Digging your Grave with your Knife and Fork after he lost 110 pounds, Mr Huckabee is vying with Mr Romney and former Tennessee senator Fred Thompson for the Christian conservative vote.
He delivered the pithiest line of the night when a questioner asked if Jesus would have supported the death penalty.
"Jesus was too smart to ever run for public office," Mr Huckabee said.
The former governor's full answer was more thoughtful, however, reflecting on the difficulty he faced in carrying out the death penalty.
"Let me tell you, it was the toughest decision I ever made as a human being. I read every page of every document of every case that ever came before me, because it was the one decision that came to my desk that, once I made it, was irrevocable."
Former frontrunner John McCain, who has struggled to keep his campaign viable in recent months, also had a good night, adopting the moral high ground in arguing against the use of "waterboarding" and other forms of torture during interrogations of terrorist suspects. "If we're going to get the high ground in this world and we're going to be the America that we have cherished and loved for more than 200 years, we're not going to torture people. We're not going to do what Pol Pot did. We're not going to do what's being done to Burmese monks as we speak.
"I suggest that you talk to retired military officers and active duty military officers like Colin Powell and others, and how in the world anybody could think that that kind of thing could be inflicted by Americans on people who are held in our custody is absolutely beyond me," he said.
The debate came hours after the release of documents from Mr Giuliani's time as New York mayor showing that he billed obscure city agencies for tens of thousands of dollars in security expenses amassed in 2001 while he was pursuing an extramarital affair in the Hamptons with Judith Nathan, now his third wife.
The documents, obtained by the website Politico under New York's freedom of information law, show that the mayoral costs had nothing to do with the functions of the little-known city offices that defrayed his tabs, including agencies responsible for regulating loft apartments, aiding the disabled and providing lawyers for indigent defendants.
Asked about the expenses during Wednesday's debate, Mr Giuliani denied any wrongdoing. He said that New York mayors were given round-the-clock security, and that he knew nothing about the expense claims.
"I had nothing to do with the handling of their records. They were handled, as far as I know, perfectly appropriately," he said.