Former Trump chief strategist Steve Bannon unleashed a torrent of insults against former President George W. Bush in California Friday night.

"President Bush embarrassed himself," Bannon said, in a 40-minute address at an annual California Republican Party convention in Anaheim, Calif. "He has no earthly idea whether he is coming or going just like it was when he was president of the United States," Bannon said to a smattering of applause and laughter.

Bannon also called Bush the "most destructive" president in American history for allowing China's rise as an economic force.

"It's clear he didn't understand anything he was talking about," Bannon continued, referring to a speech delivered by Bush just a day earlier, in which the 43rd president never alluded to President Trump by name. Bush did, however, denounce many of the policies and political tactics frequently employed by Trump and which have become synonymous with his administration — many of which political observers also associate with Bannon.

"We've seen nationalism distorted into nativism, forgotten the dynamism that immigration has always brought to America," Bush, who advocated for comprehensive immigration legislation late in his presidency, said at the Bush Institute's Spirit of Liberty event in New York City.

"We see a fading confidence in the value of free markets and international trade, forgetting that conflict, instability and poverty follow in the wake of protectionism," he added.

Bush's two-term presidency embraced the tenets of free trade. Throughout his administration, he warned against global protectionism, which he believed would stunt the nation's economic growth.

Returning to themes that Bush said are driving Americans apart, the former president said, "Bigotry seems emboldened. Our politics seems more vulnerable to conspiracy theories and outright fabrication."

(Bush wasn't the only former president this week seeming to respond to the particular style of politics that has been championed by both Trump and Bannon. "If you have to win a campaign by dividing people," former President Barack Obama said at a Virginia political rally Thursday night, "you're not going to be able to govern them. You won't be able to unite them later if that's how you start." Like Bush, Obama did not mention either Trump or Bannon by name.)

Bannon's attack on the former president a day after Bush's speech is the latest salvo in the former Trump aide's self-described "war" on establishment Republicanism.

"Right now it's a season of war on the GOP establishment," Bannon declared last week at the annual Values Voter Summit in Washington, D.C.

Since returning to his position as executive chairman of Breitbart, Bannon has launched a comprehensive effort to support anti-establishment GOP candidates who will be loyal to President Trump's agenda — even in hotly contested 2018 races for Senate seats the GOP needs to hold in order to maintain and grow its majority in Congress' upper chamber.

Presaging his efforts for the midterm cycle, Bannon recently backed former Alabama Supreme Court Chief Judge Roy Moore in a GOP primary against Sen. Luther Strange, an incumbent who had been appointed by scandal-scarred governor and who was backed by both Trump and Senate Majority Leader Mitch McConnell, R-Ky. Moore won the primary but is now in a tighter than expected general election race in traditionally deep-red Alabama.

GOP Sens. Jeff Flake of Arizona, Dean Heller of Nevada, Thad Cochran of Mississippi, Deb Fischer of Nebraska and John Barrasso Wyoming are already in Bannon's sights for 2018.

Sen. Bob Corker, R-Tenn., who Bannon had also threatened with a primary challenger, recently announced he will not seek re-election in 2018. Bannon said last week, though, that Corker, who has been an increasing critic of President Trump, is now a litmus test for other establishment Republicans. "Condemn Sen. Corker," Bannon said.

The Senate's top Republican is another litmus test for Bannon as he plots for 2018. "All of you folks that are so concerned that you're going to get primaried and defeated — there's time for a mea culpa.... say 'I'm not going to vote for Majority Leader Mitch McConnell,' " he also said in a speech last week.

In California, where Democrats hold overwhelming political power in the state government and hold both of the state's U.S. Senate seats, Bannon urged conservatives to unite against Democrats in order to retain control of Republican House seats likely to be vulnerable in 2018 — and prevent Democrats from becoming the majority in the House with the new session of Congress in 2019.

His call to action would have had a special resonance for the GOP party officials and activists gathered in Anaheim because there are five House Republicans in the Southern California area being targeted by Democrats in 2018.

Copyright 2017 NPR. To see more, visit