NORTH CHARLESTON, South Carolina (AP) — Bombastic billionaire Donald Trump doubled down Thursday on his questions about Texas Sen. Ted Cruz's eligibility to serve as president, telling his rival that his birth in Canada leaves "a big question mark on your head."
Thursday's Republican Party debate comes less than three weeks before the Iowa caucuses kick off this year's voting. Trump has led the Republican field for months, confounding Republican leaders and many of his rivals.
"You can't do that to the party," said Trump in a rough-and-tumble start to the first Republican debate of the election year.
Cruz forcefully defended his ability to serve as president, accusing Trump of raising the issue only because polls show Cruz is challenging the billionaire businessman's lead, particularly in Iowa.
"The Constitution hasn't changed — but the poll numbers have," Cruz said. The senator was born in Canada, but his mother is American, which legal scholars agree fits with the Constitution's provision that only a "natural born citizen" may be president.
The heated exchanges signaled an end to months of relative civility between Trump and Cruz, both of whom are appealing to Republican voters deeply frustrated with Democrats in Washington and sometimes with their own party leaders.
Cruz also defended his failure to disclose loans of some $1 million from Wall Street banks on federal election forms during his 2012 Senate campaign, saying it was little more than a "paperwork error."
Underscoring the split in the party that has defined the turbulent Republican primary, the more mainstream candidates on stage fought to edge their way into the debate.
On the economy and national security, the candidates offered a sharp contrast to the optimistic portrait of the nation President Barack Obama outlined in his State of the Union address earlier this week, warning that sticking with Democrats in the November election could have dire consequences.
"On Tuesday night, I watched story time with Barack Obama, and it sounds like everything in the world was going amazing," New Jersey Gov. Chris Christie said.
Cruz accused Obama of painting a rosy picture of the country's economic situation while working Americans are being "left behind." On national security, former Florida Gov. Jeb Bush suggested the country was less safe under Obama and declared Hillary Clinton, the Democratic front-runner, would be a "national security disaster."
Florida Sen. Marco Rubio went even further, saying Clinton was "disqualified for being commander in chief," accusing her of mishandling classified information and lying to the families of Americans killed in the 2012 attacks in Benghazi, Libya.
Trump also defended his call for blocking Muslims from the United States because of terror concerns emanating from abroad.