Trump and Cruz Tussle as Iowa Caucus Looms

They sparred over a Canadian birthplace and New York values, hoping to land a punch for the favor of Iowa caucus-goers.

Donald Trump and Ted Cruz took off the gloves Thursday night in a series of tussles that officially severed their long tactical bromance and promised more fights to come as the first-in-the-nation caucuses draw closer.

Pitted against one another by the moderators of the Fox Business debate in South Carolina, the two GOP frontrunners quarreled first over Trump’s concern-trolling about Cruz’s citizenship status.

“Who the hell knows if you can even serve in office?” Trump said to his Republican rival, who was born in Calgary, Alberta, to an American mother. Many legal experts say this satisfies the Constitutional requirement that the President be a natural-born citizen. Trump hasn’t disputed that, but as Cruz climbs in the polls the businessman has floated the prospect of a legal challenge to Cruz’s citizenship and begun playing the Springsteen anthem “Born in the U.S.A.” at rallies as a way to needle the Texan.

Read More: Here’s the Horror Movie That Ted Cruz Referenced at the GOP Debate

A day after first responding to Trump’s provocations, Cruz amplified his attacks Thursday in Charleston, noting that Trump had previously dismissed the birther argument.

“My friend Donald said he had had his lawyers look at this from every which way,” Cruz said. “The Constitution hasn’t changed, but the poll numbers have. And I recognize that Donald is dismayed that his poll numbers are falling in Iowa. But the facts and law here are really quite clear. Under longstanding U.S. law, the child of a U.S. citizen born abroad is a natural born citizen.”

In truth, it’s Cruz whose poll numbers have dipped a bit lately. And his campaign brain trust has grown concerned the issue was damaging his standing among Iowa GOP voters. As a result, Cruz sharpened his counterattack on Trump Thursday night, amplifying his claim that the real-estate mogul represents “New York values.”

“The values in New York City are socially liberal or pro-abortion or pro-gay marriage,” Cruz said, and the “focus is around money and the media.” Amplifying the point, Cruz pointed to a 1999 interview Trump did with Meet the Press, in which he told host Tim Russert that he was “very pro-choice.”

Read More: Trump Invokes 9/11 to Defend ‘New York Values’ From Cruz

Trump responded by hammering Cruz for his “very insulting” dig at the Big Apple. “When the World Trade Center came down I saw something that no place on Earth could have handled more beautifully, more humanely than anywhere on Earth,” the Manhattanite said.

Who got the better of their skirmishes? Not surprisingly, Cruz—a former college debate champ and Supreme Court litigator—had the better of the birther dust-up. But his chances in the caucuses don’t stand to gain much from a protracted, weedy exchange over whether or not he is actually eligible to be President.

Cruz proved he is willing to go to the mat with the primary’s schoolyard bully by pointing to Trump’s checkered record of conservatism. “The final phase of a campaign is how you differentiate yourself from everybody else,” said Cruz spokesman Rick Tyler. “We’ve arrived at that stage.”

But Trump’s evocation of the city’s strength and grace in the wake of the Sept. 11 attacks was perhaps the most poignant moment he has had in a debate.

What’s clear is that with 17 days until the Iowa caucuses, the unofficial détente is over, and the fireworks are about to begin.

With reporting by Zeke J. Miller/Charleston