As former president George W. Bush prepares to hit the campaign trail in South Carolina on Monday, the chants of “Bush lied, people died” are back. But this time they are not coming from Code Pink protesters; they are coming from Donald Trump.

It turns out the front-runner for the GOP nomination is a 9/11 “truther” who believes Bush knew 9/11 was going to happen but did nothing to stop it. Moreover, Trump says, Bush knew there were no weapons of mass destruction in Iraq but lied to the American people to get us into a Middle East war.

That puts Trump to the left of even Nancy Pelosi. At Saturday’s debate, Trump was asked whether he still felt, as he said in a 2008 interview, that it “would have been a wonderful thing” for Pelosi to “impeach Bush and get him out of office” because “he got us into the war with lies.” Trump refused to disavow his comments, declaring, “You call it whatever you want. I want to tell you. They lied. They said there were weapons of mass destruction, there were none. And they knew there were none” (emphasis added).

This is uninformed left-wing claptrap. Trump’s allegation was definitively refuted by the bipartisan WMD commission led by former senator Chuck Robb (D-Va.) and Judge Laurence Silberman. Silberman has called Trump’s allegation that Bush lied “dangerous,” writing “it is one thing to assert . . . that the Iraq war was ill-advised. It is quite another to make the horrendous charge that President Bush lied to or deceived the American people about the threat from Saddam.”

Trump also repeated his claim that then-CIA Director George Tenet gave Bush “advanced notice” of the 9/11 attacks, but Bush did nothing even though he “did know it [9/11] was coming.” Turning to Jeb Bush on the debate stage, Trump declared, “The World Trade Center came down during your brother’s reign, remember that. That’s not keeping us safe. . . . And George Bush — by the way, George Bush had the chance, also, and he didn’t listen to the advice of his CIA.”

Donald Trump just went after President George W. Bush – and Jeb Bush wasn't having it. (CBS)

This is the realm of conspiracy theory. In Republican circles, it is heresy. And in normal times, it would be disqualifying for a candidate seeking the GOP presidential nomination.

Unfortunately, these are not normal times. But if there is any state where such rantings should backfire on Trump, it is South Carolina. Jeb Bush may be polling at about 10 percent there, but George W. Bush remains the most popular Republican in the Palmetto State. A poll two months ago found that the former president had 84 percent approval among South Carolina Republicans.

Moreover, President Bush has always had a special bond with our service members and veterans, who stood with him even through the darkest times in Afghanistan and Iraq because they knew he was as committed to victory as they were. So attacking Bush on his conduct of the war on terrorism should not go over well in a state that is home to major military bases such as Parris Island, Shaw Air Force Base, Fort Jackson, Joint Base Charleston and Marine Corps Air Station Beaufort.

There are likely a significant number of Trump supporters in South Carolina who are also George W. Bush supporters. They probably did not appreciate seeing their presidential candidate viciously attack their beloved former president.

This does not mean that Trump supporters offended by his attack on George W. will suddenly rally around Jeb (who had his best debate Saturday and vigorously came to his brother’s defense). The question is: After hearing Trump spout MoveOn.org talking points, is there even a fraction of Trump supporters who will reconsider and take a second look at the rest of the GOP field?

Ted Cruz might well have benefited, but he stood silent during Trump’s anti-George W. Bush harangue. Marco Rubio did not, and he got thunderous applause when he jumped to the former president’s defense, declaring, “The World Trade Center came down because Bill Clinton didn’t kill Osama bin Laden when he had the chance to kill him,” and adding, “I thank God all the time it was George W. Bush in the White House on 9/11 and not Al Gore.”

Will any of this translate into votes? Trump had a 20-point lead in South Carolina going into Saturday’s debate, so it remains to be seen whether he will pay a price. This much is certain: If repeating the left-wing conspiracy theories about 9/11 and Iraq does not hurt Trump in South Carolina, nothing will.

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