Rivals mount fierce attack on Donald Trump

White House hopefuls Ted Cruz and Marco Rubio unleashed a barrage of attacks against Donald Trump during Thursday’s raucous Republican debate as they sought to halt the billionaire frontrunner’s seemingly relentless march to the party’s nomination.

The three candidates exchanged some of the most heated and acerbic remarks of the entire 2016 primary cycle. They often talked over one another as they battled for supremacy in the final on-stage showdown before the “Super Tuesday” series of state wide votes on March 1.

Mr Cruz and Mr Rubio mounted a furious assault against Mr Trump, blasting the frontrunner for hiring foreigners and challenging his commitment to conservative principles, but Mr Trump largely stood his ground and swatted away the attacks.

Mr Cruz called Mr Trump a “crazy zealot”.

Knowing that they need to change the campaign trail narrative quickly or risk Mr Trump coasting to the Republican nomination, the two freshman senators launched broadsides against the brash billionaire, who lashed out at his challengers in what quickly devolved into a shouting match.

Mr Rubio, seen by many as the primary mainstream challenger, appeared loose and aggressive against Mr Trump. While he has hesitated to attack Mr Trump directly on the campaign trail, Mr Rubio seemed eager to engage and criticise his rival during the debate in Houston.

He immediately berated Mr Trump over his immigration positions including having once supported a pathway to citizenship for the undocumented.

And he took him to task for having “hired a significant number of people from other countries to take jobs that Americans could have filled” in Mr Trump development projects.

Mr Rubio pointed to articles that described a 1980s lawsuit by a workers union against Mr Trump for hiring 200 illegal immigrants from Poland to build the Trump Tower in New York. Mr Trump said that if he is elected to power all the estimated 11 million illegal immigrants, which includes some 300,000 people from India, would have to go back and then enter the US through a legal process.

“We have at least 11 million people in this country that came in illegally. They will go out. Some will come back, the best, through a process. They have to come back legally. They have to come back through a process, and it may not be a very quick process, but I think that’s very fair, and very fine," Mr Trump said.

Mr Rubio also accused Mr Trump of starting a “fake university” that bilked students out of thousands of dollars, and said that if the real estate icon had not received a massive inheritance from his wealthy father he would be “selling watches in Manhattan”.

Mr Trump pushed back fiercely.

“I’ve hired tens of thousands of people,” he said in his rejoinder to Mr Rubio. “You haven’t hired one person, you liar.”

The tone reflected the fierce battle underway ahead of “Super Tuesday” next week, when 12 states, including Mr Cruz’s huge state of Texas go to the polls in perhaps the most consequential voting day of the 2016 primary campaign.

Should Trump win most of the states, it could be lights out for his rivals, who also include two lesser candidates in retired neurosurgeon Ben Carson and Ohio governor John Kasich.

Meanwhile, former Mexican President Vicente Fox called Mr Trump “crazy” and used the F-word to lash out against the US presidential candidate’s demand for Mexico to pay for a border wall.

“I am not going to pay for that f****** wall. He should pay for it. He's got the money,” Mr Fox told Fusion in an excerpt of the interview on the US television’s website.

Mr Trump quickly hit back on Twitter, writing: “Vicente Fox horribly used the F word when discussing the wall. He must apologise! If I did that there would be a uproar!”