Las Vegas - Republican presidential hopefuls put the war against ISIS front and center on Tuesday as they debated how to keep America safe, with Donald Trump under attack for demanding a ban on Muslims entering the country.
Just weeks after deadly attacks in Paris and San Bernardino, California, Republicans vying for their party's nomination in the 2016 race for the White House were suddenly confronted with the specter of terrorism on US soil and the steps they would take to defeat the ISIS entrenched in Iraq and Syria.
But amid pronouncements that US freedoms are under attack, several of Trump's rivals aimed criticism at the billionaire real estate mogul over his incendiary anti-Muslim remarks at the debate, the last for the Republicans in 2015.
"We can't disassociate ourselves from peace-loving Muslims. If we expect to do this on our own, we will fail," said former Florida governor Jeb Bush, whose campaign has failed to gain major traction over the past year.
Trump is "great at the one-liners," Bush added, "but he's a chaos candidate and he'd be a chaos president."
Senator Marco Rubio, who has been on the rise with seven weeks to go before voters in the heartland state of Iowa cast the first ballots in the nominations process, dismissed Trump's ban, simply saying the proposal "isn't going to happen."
Senator Rand Paul piled on. "I think if we ban certain religions, if we censor the Internet, I think that at that point, the terrorists will have won," he said.
Trump, the tycoon and onetime reality television star who has been the surprise leader of the Republican presidential race, has only gained in popularity since his abrasive anti-Muslim comments, even as rivals accused him of playing into jihadist hands.
Two polls unveiled Monday and Tuesday show Trump at new heights, with maverick US Senator Ted Cruz surging into second place and looking to rattle the frontrunner in the Las Vegas showdown featuring nine candidates.
But Cruz stepped gingerly when it came to criticizing Trump. The Tea Party-backed senator suggested he was opposed to letting in refugees from Middle East war zones who cannot be properly vetted.
"We will not be admitting jihadists as refugees. We will keep America safe," Cruz said.
'We need toughness'
The debate is the first since the Paris and San Bernardino attacks, violence that has brought national security concerns to the fore and heightened Americans' fears about illegal immigration and Syrian refugees.
Those fears likely played prominently in recent surveys, including a Monmouth University poll released Monday showing 41% of Republican voters support Trump, his highest position yet in the poll.
Cruz surged to 14%, with 10% for Rubio and 9% for retired neurosurgeon Ben Carson. All others are at three percent or lower.
In an ABC News/Washington Post poll on Tuesday, Trump earned 38% support among registered Republicans and GOP-leaning independents, a six-point climb from November.
Despite his runaway lead, Trump was largely absent from the detailed debate over strategy to defeat the IS group, instead clashing with rivals like Bush and Paul who took shots at the tycoon for not being a serious candidate.
"He's a very nice person," Trump said of Bush, "but we need toughness."
The prime-time event also featured New Jersey Governor Chris Christie, who said his experience as a federal prosecutor makes him the most experienced in going after terror suspects.
Business executive Carly Fiorina, former CEO of Hewlett-Packard, said she would use her technological expertise to lead the fight against extremism.
And while Ohio Governor John Kasich called for a coalition to bring about the total destruction of the Islamic State group, "we must lead or the job won't get done."
Four lower-polling candidates took the stage earlier in an undercard debate, with hawkish Senator Lindsey Graham extending an olive branch to peace-loving Muslims.
"Donald Trump has done the one single thing you cannot do: declare war on Islam itself," said Graham, who advocates sending 10 000 US troops to Syria and Iraq to help Arab allies defeat ISIS.