Jeb Bush and John Kasich challenged Republican presidential frontrunner Donald Trump on his controversial plan to deport millions of immigrants who are in America illegally — a plan that happens to be popular among the Republican base.
It was one of a few intense moments in a debate Thursday night that, until late, lacked the direct confrontations of the three earlier GOP debates of the 2016 campaign as the Fox Business Channel and Wall Street Journal moderators focused on the minimum wage, tax plans and trade deals.
But the fireworks came when the discussion turned to immigration and foreign policy.
Trump repeated his promise to deport 11 million immigrants living in the U.S. without documentation, while building a border wall between the country and Mexico.
When John Kasich, the governor of Ohio, said "we all know you can't pick them up and ship them across the border," Trump dismissed him out of hand.
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"I've built an unbelievable company worth billions and billions of dollars. I don't have to hear from him," said the billionaire real estate mogul.
Bush, the ex-governor of Florida, stood up for Kasich at Trump's invitation. Considered the standard-bearer of centrist conservatives in this election before he started flagging in the polls, Bush railed against Trump and the notion of deporting people. It would be un-American, he said, and would tear communities apart.
"They're doing high fives in the Clinton campaign now when they hear this," he added. Apparently, he was right, according to a tweet from Clinton's press secretary.
Opposing Trump's deportation plan might have been a risky move; earlier this year, Trump's plan has had support among Republicans paying attention to the debate. Almost half of Republicans polled in Iowa in early September said they thought deporting 11 million immigrants in the U.S. illegally was a good idea, while 37 percent disagreed.
Foreign policy sparked another minor powder-keg later on in the debate, after Marco Rubio called fellow U.S. Sen. Rand Paul a "committed isolationist" after an answer about America's military budget.
Paul shot back: "How is it conservative to add a trillion dollars in military expenditures?"
A few of other candidates joined in, supporting Rubio in saying the U.S. has to maintain the world's strongest military for its own safety.
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"Try not defending it, that's a lot more expensive," Sen. Ted Cruz said.
"We have to make our military bigger, better, stronger than ever before, so that nobody messes with us," Trump said.
But Bush and former HP CEO Carly Fiorina didn't resist jabbing Trump on foreign policy.
Trump said he'd be fine with Russia's Vladimir Putin playing a role in trying to "knock the hell" out of the Islamic State in Syria. But Bush dismissed that as a "board game" view of the world.
"We're not going to be the world's policeman but we sure as hell should be the world's leader," Bush retorted.
And Fiorina said she wouldn't negotiate with Putin, arguing that the U.S. should bolster the military in the Middle East so it has a stronger bargaining position – something Trump should know because he "fancies himself a very good negotiator," she said in a reference to his bestselling book "The Art of the Deal."
Fiorina also jabbed Trump for having touted a meeting with Putin while "stablemates" the same day both interviewed with "60 Minutes." Fiorina said she had also met Putin, "not in a green room for a show, but in a private meeting."
Still, NBC News reported that Fiorina has previously described meeting with Putin in "sort of a green room setting."
“I met him in Beijing. We were in sort of a green room setting," she said in a September "Tonight Show" appearance. "Each of us were giving a speech at a major economic conference called APEC.”
Soon after Tuesday's exchange, Trump intervened while Fiorina tried to inject herself into another exchange on foreign policy while Paul was speaking.
"Why does she keep interrupting everybody?" Trump said. The comment led to boos from the audience.
The Associated Press contributed to this report.
