Dumping Trump: Four ways Republicans might take on Trump
Donald Trump's recent pronouncement that the US should close its borders to all Muslim immigrants until the nation can "figure out what's going on" has given a renewed sense of urgency to establishment Republican efforts to derail his candidacy.
While polls show that Mr Trump's position has the support of many party faithful, it could be general election poison. A recent survey, for instance, has Mr Trump faring poorly against Democrat Hillary Clinton compared to his Republican rivals. And yet, according to another poll, the candidate has opened a massive lead over his competition.
So as Republican candidates gather in Las Vegas on Tuesday for the party's last presidential debate of 2015, they're faced with an overriding question. What's the best way to beat the brash billionaire before it's too late?
Here are four possible strategies.
It may be hard to remember, but it was once thought that the best way to defeat Mr Trump was to pretend he wasn't there. In the first Republican debate, back in August, candidates like former Florida Governor Jeb Bush and Wisconsin Governor Scott Walker effectively screwed their eyes shut and plugged their ears whenever he spoke.
The result was that Mr Trump ploughed through them, making the candidates seem weak and irrelevant. Mr Walker's campaign is now a historical footnote, and Mr Bush is languishing in single digits.
Some Republican presidential hopefuls may continue to talk over, under and around Mr Trump, but they do so at their peril.
Like a mythical beast of old, The Donald has been the undoing of many candidates who have sought to test their mettle against the front-runner.
Texas Governor Rick Perry? Louisiana Governor Bobby Jindal? They charged headfirst into the Trump buzzsaw and are now licking their wounds at home. Ohio Governor John Kasich made a run at the real-estate mogul during the last debate and was cut to ribbons.
Given the level of outrage that Mr Trump's Muslim border ban generated last week, however, some candidates may figure the time is ripe for another frontal assault.
A "have you no decency" style soliloquy could be just the trick for candidates like Mr Bush, New Jersey Governor Chris Christie or Florida Senator Marco Rubio, looking to rally the anti-Trump forces to their banner.
Or it could end in disaster, as Mr Trump once again gives better than he gets.
If Mr Trump is a classic bully, as his detractors often say, what better way to defeat him than with humorous derision? Take away a bully's ability to intimidate and demean, and he loses his power.
It's a lesson that Mr Kasich's team has perhaps learned. After the candidate's ill-fated debate fireworks and a television advertising campaign questioning Mr Trump's fitness to lead, a super-PAC supporting the Ohio governor is now running a 75-second video that ridicules the New Yorker as a failed steak huckster.
When Mr Trump called Ted Cruz a maniac this weekend, the Texas senator responded by tweeting a video of a song by the same name from the 1980s film Flashdance.
Needling like this could prompt an angry response from Mr Trump, of course. But when the New Yorker hits back against attacks, he looks strong. If he punches back against humour, he could look small and thin-skinned.
A much-anticipated poll released on Sunday showed that Mr Cruz has vaulted ahead of Mr Trump as the top preference of likely Republican participants in Iowa's first-in-the-nation caucus. The Texan has done so by deliberately avoiding any conflict with Mr Trump, direct or otherwise.
Mr Cruz was surreptitiously recorded explaining his strategy during a closed-door meeting with deep-pocketed donors in New York last week. He said he planned to "bear hug" Trump and fellow outsider Ben Carson and "smother them with love", then collect their supporters when they eventually begin looking for a more serious, electable candidate.
Mr Cruz will likely stay the course on Tuesday night, and other candidates, seeing his success, may follow his lead - or even direct their fire at the new hot hand.
Mr Carson already is on the record saying he'll stand with Mr Trump if the Republican establishment tries an end run around the nomination rules to block one of them from winning.
Perhaps the way Mr Trump loses is for other candidates to act just like him.
Then again, that sounds a lot like a way Mr Trump wins.