Republicans brace for fallout from Donald Trump's offensive comments about Mexican immigrants
Donald Trump speaking at CPAC 2011 in Washington, D.C. (Gage Skidmore/Flickr)

Like a brush fire kicking up in America's southwest, the storm brought on by Donald Trump's political bombast threatens to scorch all it touches as Republicans brace for fallout from their rival's remarks.

The billionaire tycoon's caustic, seemingly unrehearsed comments about Mexican immigrants, uttered when he launched his White House campaign in mid-June, sparked immigration debates and triggered questions about the braggadocio of a candidate unafraid to disparage fellow Republicans, and whether it hurts the party's chances in 2016.

His business interests have taken a hit, with Univision, NBC and retailer Macy's severing ties with Trump after the mogul saidMexico was sending "rapists" and other criminals into the United States.

But his political profile -- fuelled by non-stop media coverage in recent weeks -- has risen substantially.

"The Donald," as he is sometimes nicknamed, has emerged as the number-two contender, behind Jeb Bush, in recent polls by CNN and Fox.

"He's huge right now," Gregory Valliere, chief political strategist at the non-partisan Potomac Research Group, told AFP.

"He'll make more astounding gaffes and eventually self-destruct, but that could take a while."

The party's leadership has sought to douse the flames, with Republican National Committee chairman Reince Priebus calling Trump this week, discussing Trump's comments about illegal immigration and apparently urging him to tone down the rhetoric.

But Trump has kept at it, doubling down on his message, boasting to NBC News that, "Frankly, if I didn't bring it up, you wouldn't even be talking about immigration right now."

Bush, whose wife is from Mexico, denounced Trump's views as "way out of the mainstream." Candidate Rick Perry, a former Texas governor, said he was "offended" by Trump's remarks.

- 'Enormous' danger -

Trump was scheduled to address the controversial issue again Saturday in the border state of Arizona, where his event has been moved to a larger venue due to overwhelming demand, according to his campaign.

But Arizona's Senator John McCain is shunning Trump and won't be there. On Friday the 2008 Republican nominee, who in 2013 helped lead ultimately failed efforts at comprehensive immigration reform, dismissed the ongoing debate as a "circus" which "sows division within our country and damages the Republican Party."

The party led an exhaustive post-mortem on its 2012 election defeat, and concluded that it needed to reach out more to Hispanics, who enjoy increasing clout in presidential elections, if it wanted a shot at reclaiming the White House.

Analysts and observers warn that Trump's bluster might jeopardize such efforts.

"This has become an area of concern for the Republican Party, even if Trump's candidacy goes nowhere or he quits," said Professor Peter Kastor, who chairs the history department at Washington University in St Louis and studies the presidency.

"It doesn't help the Republican brand."

Trump has floated the idea of running as a third-party candidate, something that could give Republican strategists nightmares.

The move would recall the challenges of fellow billionaire Ross Perot, who split the Republican vote and helped Bill Clinton win in 1992, and Ralph Nader, who was accused of acting as spoiler in 2000 when George W. Bush narrowly defeated Al Gore.

"Almost every election in the 20th century featured the fear of an out-of-control candidate," Kastor said. "They've never won, but they do have an impact."

That theory will be tested August 6, when Republicans hold their debut debate.

The Republican field will feature 16 candidates, but Fox News, which broadcasts the debate live, has said only Republicans polling in the top 10 make the stage. If current numbers hold, Trump will be among them.

With a displayed willingness to eviscerate rival candidates, Trump could be an "enormous" danger in debates, Valliere said.

Other participants "risk losing any ability to control where the debate's going, because everyone is stuck revolving around Donald Trump," added Kastor. "The other side of this is that ratings soar."

Despite being one of the most famous people in America, with enviable business acumen and pledges to get tough on nations like China, Trump will not win the nomination, insisted Karlyn Bowman, a scholar at the American Enterprise Institute, a conservative think tank.

"He just has too many weaknesses."

In the end, Bowman added, he could eventually bow out by saying, "'It's time for me to go back to concentrating on business.'"