It’s no secret that Donald Trump is a vicious bastard. It’s no secret that his views have often been more aligned with liberals than with conservatives. But until tonight, I didn’t know that his stance on George W. Bush is more vicious than that which leftist politicians are willing publicly to take. Nor did I know that Trump once urged Nancy Pelosi to impeach President Bush.

In tonight’s debate, Trump claimed that the Bush administration knew in advance of the invasion of Iraq that Iraq did not possess weapons of mass destruction. This is a ludicrous assertion. No president would be stupid enough to invade a country based on the claim that it has WMD, knowing that the claim would be exposed as false by the invasion itself.

Thus, even leftist politician normally don’t level Trump’s allegation at President Bush. Whatever they may say in private, they have left this vicious claim to the “Bush lied, people died” protesters — i.e., to Code Pink and its ilk.

Trump also blamed President Bush for the attack on the World Trade Center. This claim is less outrageous and more common than the assertion that Bush knew Iraq didn’t have WMD. But it’s still unfair, given the short amount of time Bush had been in office as of 9/11. And it’s not something one expects to hear from a candidate with realistic aspirations to win the Republican nomination.

Similarly, one doesn’t expect such a candidate to have talked with Nancy Pelosi about impeaching a Republican president. Yet, when confronted with this allegation, Trump didn’t deny it. Instead, he said he gets along with everyone. Everyone except the only Republican president in the past 23 years, it seems.

Will Trump’s vicious attacks on George W. Bush hurt him in South Carolina? I’ve read that the ex-president’s approval rating among Republicans there exceeds 80 percent. The fact that Jeb Bush has enlisted his brother to campaign for him South Carolina seems telling.

But Trump probably only needs about 30 percent of the South Carolina vote to win the primary. I don’t assume that attacking President Bush will prevent the tycoon from reaching that mark, but we will see.

I do suspect that the viciousness of the attack will hurt Trump down the road. There will come a time when Trump needs 40 percent of the vote to win primaries. In a two-way race, if we ever get there, he will need 51 percent.

Polls have shown that Republican opposition to Trump is substantial. After tonight, it may solidify and grow.

There’s also a general election that Trump would have to win in order to become president. To win it, he would need solid, across-the-board support from Republicans. The viciousness of Trump’s attack on Geroge W. Bush may cause reconsideration on the part of many Republicans who had intended, if it came down to it, to hold their nose and vote for Trump. (Nor can Trump expect the votes of the Code Pink crowd no matter how viciously he attacks Bush).

Why did Trump, who appears to hold a big lead in South Carolina, risk alienating Republicans by attacking the popular brother of a candidate who is running a distant fourth in South Carolina? That’s an easy one for those who have been paying attention to Trump. George W. Bush is coming to South Carolina to campaign for Jeb. Anyone who dares oppose Trump, even just by supporting someone else, must be smeared.

This is the modus operandi of the Clintons and the Obama administration. The only difference I can detect is that Trump seems to enjoy engaging in the politics of personal destruction more than Bill, Hillary, and Obama.