Steve Bannon shared an unforgiving critique Friday of former President George W. Bush just one day after the 43rd president delivered an implicit rebuke of President Trump.

Speaking to the California Republican Party convention, Bannon, Trump's former chief strategist, called Bush a "piece of work." He said Bush "embarrassed himself" and had no idea what he was talking about "just like it was when he was president of the United States."

Focusing on Bush's eight years in the White House, Bannon said, "There has not been a more destructive presidency than George Bush's."

Bush delivered a speech in New York on Thursday, during which he spoke about how in the present "bigotry seems emboldened" and of "nationalism distorted into nativism." He never said Trump's name, but many politicos and journalists made the inference that he was speaking about Trump.

According to CNN's Maeve Reston, there were some cheers when Bannon condemned Bush, but she also noted that many others were silent.

It's no secret that there is no love lost between Bannon, who is back as executive chairman of Breitbart News, and the Bush team. Last month he described the Bush administration as a bunch of "idiots" during a "60 Minutes" interview on CBS.

"I hold these people in contempt, total and complete contempt," he said while harping on their foreign policy and national security blunders.

Meanwhile, one former Bush adviser, Karl Rove, wrote "good riddance" in an August op-ed after Bannon left the White House.

"Mr. Bannon is not the first staffer to believe the White House agenda must mirror his own. But no other aide in memory has had such grandiose or destructive plans for trying to remain in charge after being shown the door," he wrote in the Wall Street Journal.

Bannon appeared to refer to this "very unfriendly" piece during his speech in Anaheim. But, he explained he didn't mean to mention Rove by name. "I don't like punching down," he said.

The speech Friday evening came amid Bannon's so-called "season of war" effort to unseat establishment Republicans in the Senate in 2018. He has already seen victory in Alabama with his preferred candidate, Roy Moore, beating out Trump and Senate Majority Leader Mitch McConnell's favored Sen. Luther Strange in last month's GOP run-off contest to reach the election to fill the Senate seat vacated by Attorney General Jeff Sessions.

Bannon has aligned himself with Trump since leaving with the White House, even though they don't always see eye-to-eye on everything. Case-in-point was the Alabama special election. Bannon didn't fault Trump for choosing Strange, instead, saying Friday that Trump got "bad information."

A few dozen protesters had gathered outside before his speech, upset with Bannon's position on intra-party fighting.

Despite the mixed reaction to Bannon's criticism of Bush, the end of his speech, which also focused on California politics, was met by a standing ovation, CNN's Miguel Marquez reported.