Former White House adviser Steve Bannon widened his assault on the Republican establishment Friday night, saying former GOP President George W. Bush had the most “destructive” presidency in U.S. history.

Bannon's scathing comments at the annual California Republican Party convention came about a week after Bush denounced bigotry in Trump-era American politics and warned that the rise of isolationism and "nativism," which Bannon espouses, have clouded the nation's true identity.

"There has not been a more destructive presidency than George Bush's," Bannon said.

He also said Bush has no idea whether "he is coming or going, just like it was when he was president,” amid boos in the crowd at the mention of Bush's name.

Bannon made the remarks in a speech thick with attacks on the Washington status quo, echoing his earlier calls for an "open revolt" against establishment Republicans. He called the "permanent political class" one of the great dangers faced by the country.

Bannon, a late-arrival to Trump’s presidential campaign who was ousted last month from his White House post, got a standing ovation at the conclusion of his speech in Anaheim.

Since leaving the White House as Trump’s top political adviser, Bannon has returned to Breitbart News and embarked on an effort to unseat Senate Majority Leader Mitch McConnell and other congressional Republicans whom he thinks have slowed or blocked Trump’s legislative agenda.

Bannon has for weeks basked in the victory of social conservative Roy Moore over establishment candidate Sen. Luther Strange in Alabama’s GOP Senate runoff.

And at a speech last weekend in Washington to social conservatives, Bannon declared “war” on establishment candidates, particularly lose seeking reelection next year.

A small group of protesters gathered outside the Southern California hotel where Bannon spoke, chanting and waving signs including one with a Nazi swastika. The protesters were kept behind steel barricades on a plaza across an entrance road at the hotel, largely out of view of people entering for the event. No arrests were reported.

Bannon also took aim at the Silicon Valley and its "lords of technology," predicting that tech leaders and progressives in the state would try to secede from the union in 10 to 15 years. He called the threat to break up the nation a "living problem."

He also tried to cheer long-suffering California Republicans, in a state that Trump lost by over 4 million votes and where Republicans have become largely irrelevant in state politics. In Orange County, where the convention was held, several Republican House members are trying to hold onto their seats in districts carried by Hillary Clinton in the 2016 presidential contest.

"You've got everything you need to win," he told them.

While Bannon is promoting a field of primary challengers to take on incumbent Republicans, the GOP has been fading for years in California.

The state has become a kind of Republican mausoleum: GOP supporters can relive the glory days by visiting the stately presidential libraries of Ronald Reagan and Richard Nixon, but today Democrats control every statewide office and rule both chambers of the Legislature by commanding margins.

Not all Republicans were glad to see Bannon. In a series of tweets last week, former state Assembly Republican leader Chad Mayes said he was shocked by the decision to have the conservative firebrand headline the event.

"It's a huge step backward and demonstrates that the party remains tone deaf," Mayes tweeted

Political scientist Jack Pitney, who teaches at Claremont McKenna College, said he doubted the speech would color the 2018 congressional contests, which remain far off for most voters.

More broadly, he said Bannon's politics would hurt the GOP, including among affluent, well-educated voters who play an important part in county elections.

"Inviting him was a moral and political blunder," Pitney said in an email.

The Associated Press contributed to this report.