US President Donald Trump's ex-strategist Stephen Bannon calls George W. Bush presidency 'most destructive'

Former US President George W. Bush waves to the crowd prior to foursome matches of the Presidents Cup at Liberty National Golf Club on September 28, 2017 in Jersey City, New Jersey.

Former chief strategist to US President Donald Trump has fiercely criticized former Republican President George W. Bush, referring to his legacy as the most “destructive” while questioning his intellect.

“There has not been a more destructive presidency than George Bush’s,” said Bannon late Friday during a convention banquet for the Republican Party of California -- a predominantly Democratic state – as part of his proclaimed “season of war” against the country’s “Republican establishment.”

The remarks by the ultra-right media figure, who also led Trump’s successful presidential campaign, came after Bush delivered a speech on "democracy and security" Thursday, saying that “bigotry seems emboldened” in the US and calling on Americans to reject “white supremacy.”

Further criticizing the country’s “governing class” without identifying any politician, the ex-president added, “Our politics seem more vulnerable to conspiracy theories and outright fabrication.”

In an apparent reaction to the speech by Bush, Bannon emphasized that "It was clear he didn't understand anything he was talking about. He has no earthly idea of whether he's coming or going, just like it was when he was president of the United States."

File photo of US President Donald Trump (L) congratulating appointed Chief Strategist Stephen Bannon during the swearing-in of senior staff in the East Room of the White House in Washington, DC on January 22, 2017. (Photo by AFP)

The remarks by Bannon came a week after he declared a “season of war” on Republican lawmakers heading into the 2018 midterm elections. He is backing primary challengers in multiple states, after his candidate, former judge Roy Moore, successfully won the special Alabama Senate primary against an establishment -- and Trump-backed the opponent.

Bannon’s speech was reportedly well received and ended with a standing ovation during the California event.

The development came as rival Democratic Party Chairman Tom Perez described Trump as the most dangerous president in history, while calling for party unity against a Republican culture of corruption in preparation for next year’s mid-term congressional elections.