Greenville - Donald Trump and Jeb Bush took the gloves off on Saturday in the Republican presidential debate, with the billionaire frontrunner unleashing a tirade of intense and often personal attacks one
Trump, seeking to blunt Bush in a state where his dynastic family remains popular, went after the former Florida governor on foreign policy and immigration, and lambasted Jeb's brother president George W Bush's war in Iraq as "a big fat mistake".
Trump was relentless in badgering Bush, even saying Jeb's mother should have been the Bush candidate instead.
"Jeb is so wrong," Trump said, to loud boos from the audience, people whom Trump dismissed as lobbyists and establishment Republicans.
Bush parried back, hitting Trump's suggestion he could work with Russia to combat the Islamic State jihadist group in Syria and Iraq.
"You can't fight two wars at one time," Trump said, adding that Bush experts have been deeply misguided about Middle East policy.
Bush countered that Trump gets his foreign policy from "the shows", while Bush's brother was formulating policy to protect Americans.
"While Donald Trump was building a reality TV show, my brother was building a security apparatus to keep us safe. And I'm proud of what he did," Bush said.
"The World Trade Center came down during your brother's reign," Trump shot back. "Remember that."
It was an extraordinary back and forth on the national stage, with candidates often ignoring the moderators and going after each other in perhaps the most aggressive exchanges of the nine Republican debates to date.
"We're in danger of driving this into the dirt," one of the CBS debate moderators said at one point.
Trump is leading in polls in South Carolina, but Bush is counting on the state to boost his fortunes as the race turns to the south. Trump sought to take him down early in the debate, in part by denigrating Bush's brother George W. (president 2001-2009).
"I'm sick and tired of him going after my family," Bush said.
Trump also attacked Senator Ted Cruz, his nearest rival, as a "liar" and a "nasty guy".
Senator Marco Rubio also unleashed a zinger against Cruz, who like Rubio is Cuban-American, when Cruz attacked him over immigration policy comments he made on Spanish-language Univision television.
"I don't know how he knows what I said on Univision because he doesn't speak Spanish," said Rubio, who is fluent in the language.