US Senator Marco Rubio has lashed out at rival Republican front-runner Donald Trump at the GOP Debate on Thursday night targeting a number of controversial issues, trying to gain grounds over the latter. Rubio tried to throw Trump off his footing by criticising his business records and lashing out at issues like the alleged hiring of “illegal migrants” and a “fake university” with his name.

“If he hadn’t inherited $200 million, you know where Donald Trump would be? Selling watches in Manhattan,” the Washington Post quoted Rubio as saying.

To this, Trump responded by saying that Rubio has never handled a business himself and he has exaggerated the inheritance the former got from his father. Trump also cited a case in which Rubio reportedly sold a house to a lobbyist and gained significant profit.

“He sells it to a lobbyist, who’s probably here,” Trump said.

The two candidates have been involved in a heated up debate until Trump asked the moderator whether he can respond.

Rubio referred to the former Trump University, which is facing a fraud case, as a “fraud school.” He also attacked Trump by bringing up allegations against the latter who purportedly allowed illegal migrants from Poland to take up jobs that Americans could have filled.

Trump rejected the allegations and returned the criticisms by saying, “I’m the only one on the stage that’s hired people. You haven’t hired anybody.”

Rubio held on to his allegations and was backed by Senator Ted Cruz from Texas. Rubio later contended that Trump lied regarding the Polish workers.

“I guess there’s a statute of limitations on lies,” the Fox News quoted Rubio as saying.

At the debate, Trump also reiterated his promise to build a wall at the US-Mexico border if elected. This came after former Mexican President Vicente Fox said Mexico is not interested in paying for the wall.

“I will, and the wall just got 10 feet taller, believe me,” Trump said.

The faceoff at the GOP Debate came as the last chance for the candidates to break Trump’s momentum, which has intensified after the three straight primary and caucus wins he got before Super Tuesday.

At the same forum, Cruz said that he is the only viable alternative candidate since he is the only other nominee to win a primary contest, the Iowa Caucuses. He said that his campaign is “the only campaign that can beat Donald [and] has beat Donald.”

The Republican Debate, which is being aired on CNN, can also be watched for free by streaming online at the The event began at 8:30 pm Easter time [11:30 AM AEST].