A group of conservatives in one corner of Capitol Hill rejoiced as shockwaves rippled through Washington on Tuesday when Arizona Sen. Jeff Flake announced his plan to retire next fall in a dramatic floor speech.

Allies of former White House chief strategist Steve Bannon, who vowed to target Flake in the 2018 midterm election, touted the unexpected decision by Arizona's "Never Trump" senator as a clear victory for the GOP's anti-establishment wing.

"This is the Bannon effect in action," an ally close to Bannon said in a text minutes after Flake announced his forthcoming retirement, citing the current political environment as the primary reason behind his exit after just one term in the upper chamber.

"Never Trump Senators and allies of [Sen. Mitch] McConnell beware," the Bannon ally warned.

Flake's decision capped off "a stretch of undeniable success," as another Bannon ally put it.

The fiery Breitbart chairman, a self-described economic nationalist, organized a high-profile rally for Alabama Senate candidate Roy Moore on the eve of his run-off election against incumbent GOP Sen. Luther Strange late last month. When Moore soundly defeated Strange, whom Trump had endorsed and campaigned for, Bannon said it was the beginning of the end for establishment-friendly Republicans.

And when Sen. Bob Corker announced his own plan to retire after 2018, potentially paving the way for Congresswoman Marsha Blackburn, a steadfast Trump supporter, to run for his seat, Bannon said it marked "a season of war against the GOP." He later suggested the Tennessee Republican resign immediately.

"Bannon has three scalps so far: Corker, Strange, and now Flake," Sam Nunberg, a former Trump adviser and Bannon ally told the Washington Examiner.

"It's no coincidence that Flake officially dropped out only a week after Laura Ingraham and Steve Bannon campaigned for [pro-Trump Arizona Senate candidate] Kelli Ward," Nunberg continued. "This Bannon Movement is real."

In remarks to his colleagues Tuesday afternoon, Flake said he did not regret criticizing President Trump in the months leading up to his announcement of retirement.

"The notion that one should stay silent as the norms and values that keep America strong are undermined and as the alliances and agreements that ensure the stability of the entire world are routinely threatened by the level of thought that goes into 140 characters — the notion that one should say and do nothing in the face of such mercurial behavior is ahistoric and, I believe, profoundly misguided," the freshman senator said in a speech on the Senate floor.

Bannon endorsed Ward for Flake's seat shortly after his deep-pocketed ally, Robert Mercer, contributed $300,000 to a super PAC aligned with her in early August.