Donald Trump has attacked Ted Cruz over his birth in Canada in the latest Republican debate for White House hopefuls.
The Republican front-runner said Texas Senator Ted Cruz’s birth in Canada raised questions about his presidential eligibility: “There’s a big question mark over your head.”
The constitution mandates the president be a “natural born citizen” of the US.
Issues of national security, the economy and foreign policy have also played heavily in the debate.
In the polls, Donald Trump and Ted Cruz are leading the five other candidates who were also on the stage in North Charleston.
The debate came just two weeks before the first real test of the campaign, when voters in Iowa pick their Republican and Democratic choices for president.
The event hosted by Fox Business Network came after days of Ted Cruz and Donald Trump taking shots at each other, shattering a months-long period of goodwill between the two men.
The start of hostilities began a week ago when the billionaire businessman started raising questions about whether the Texas senator’s birth in Canada put his eligibility in doubt.
However, on the debate stage on January 14, Ted Cruz said there was “zero chance” of a lawsuit succeeding, because the constitution’s definition of “natural born citizens” included people born to an American parent.
Ted Cruz was born in Calgary to an American mother and a Cuban father.
Donald Trump stood firm, noting that a Harvard law scholar had raised doubts and Ted Cruz could face lawsuits by Democrats wishing to challenge his qualification.
They also argued over the meaning of “New York values”, which Ted Cruz threw at the New York billionaire as a slur on his conservative credentials.
Donald Trump said that was an insult to the “great people” who pulled together after the 9/11 attacks.
After the debate, Donald Trump told reporters: “I guess the bromance is over.”
All the candidates targeted leading Democratic candidate Hillary Clinton, who was repeatedly attacked for her time as Secretary of State.
The primary contests, in which each party picks their nominee for president, begin in February and the presidential election is in November.