The unexpected retirement of U.S. Jeff Flake, R-Ariz., will likely further inflame the Republican Party's civil war -- with former White House chief strategist Steve Bannon racking up the fruits of victory in his bid to reshape the party.

Flake announced his resignation Tuesday with a scathing attack on Trump from the Senate floor, calling the commander-in-chief’s behavior “reckless, outrageous, and undignified."

The senator also slammed the GOP, saying it had “given in or given up on the core principles in favor of a more viscerally satisfying anger and resentment,” and noted that “anger and resentment are not a governing philosophy."

But Flake's speech was likely music to the ears of Bannon, who has announced plans to run pro-Trump candidates against Senate Republicans who don't back the president's agenda. And Flake's emotional speech was unlikely to change the views of GOP voters who see establishment Republicans such as Flake as obstacles for executing Trump's “America First” agenda.

Recent polls show there is little appetite among voters for anti-Trump legislators in the Senate, especially in Arizona – a state Trump carried in 2016 presidential election. Flake was trailing his primary challenger, Kelli Ward, a former state senator who is backed by Bannon.

After Flake's announcement, Bannon quickly claimed a scalp for his anti-GOP establishment movement, warning incumbents that his recruited candidates “will defeat you in primaries or force you to retire," according to Breitbart News Network Editor-in-Chief Alex Marlow, who tweeted the reaction.

"The days of establishment Republicans who oppose the people's America First agenda are numbered," Bannon added.

“Many more to come,” Bannon wrote to the Washington Post following Flake’s speech.

Andy Surabian, an adviser for Bannon's pro-Trump political PAC, Great America Alliance, told the Post that the resignation of Flake was a victory for the White House.

“This is a victory for President Trump and all of his supporters across the nation,” he said. “Jeff Flake was America’s top ‘Never Trumper,’ so getting his scalp is a signal to Never Trumpers everywhere that their time is up.”

From Alabama to Mississippi to Nevada, Bannon-backed candidates are emerging to challenge the establishment Republicans during the 2018 midterm elections, potentially reshaping the party beyond recognition.

And while the GOP is coming to realization that opposing Trump is bad politics, some top Republicans have criticized Bannon’s strategy to strengthen pro-Trump elements in Congress by replacing existing GOP senators rather than increasing the majority and taking seats from Democrats.

“Bannon’s so-called ‘war against the GOP establishment,’ is the worst strategic action Republicans could take right now,” wrote Former House speaker Newt Gingrich, noting that the candidates Bannon seeks to replace are senators who voted overwhelmingly for Trump’s agenda despite their public comments.

Noted Gingrich: "All voted to repeal Obamacare; all supported President Trump’s Cabinet nominations; all supported the American Health Care Act; all supported the so-called Skinny Repeal of Obamacare; and all voted to confirm conservative Supreme Court Justice Neil Gorsuch.”