While it is unusual for a former White House official like Bannon to trash a fellow top aide on the record -- in this case, Jared Kushner, the President's son-in-law -- the comments are a continuation of a long-running feud between the two men.
After Bannon spent the last several weeks lobbing criticism at President Donald Trump's inner circle and questioning the way the White House operates, tensions boiled over Wednesday after Bannon was quoted calling a meeting between Kushner, Donald Trump Jr. and a Russian lawyer "treasonous" and "unpatriotic" in excerpts from Michael Wolff's forthcoming book "Fire and Fury: Inside the Trump White House."
Trump unleashed on Bannon in an lengthy statement where he dismissed Bannon's political influence and questioned his mental stability, and although the President is known for maintaining contact with people he has fired, he spent Wednesday privately telling people he was done with Bannon.
After Bannon left the administration in August and returned to his perch at Breitbart News, the question was whether he would remain an ally of the President's or become a thorn in the administration's side.
But on Wednesday, in the White House's eyes, Bannon became more than just a nuisance. A source close to the West Wing says he crossed a clear line when he went after the President's family, noting that Bannon went from being an occasional annoyance to an adversary.
"Once Bannon got personal, the gloves were off," the source said. "They are holding nothing back."
During his time at the White House, Bannon spearheaded a nationalist faction of aides within the West Wing, often clashing with a more global-minded group that included Ivanka Trump, Kushner and chief economic adviser Gary Cohn. Those early months of the Trump administration were rife with drama from those competing power centers.
Anecdotes quickly emerged of Ivanka pleading with her father to moderate his positions -- or at least his tone -- often, with little success. It took a while to determine those leaks weren't entirely the result of her Manhattan friends casting her in the role of their liberal savior, but rather her newfound White House colleagues looking to undermine her influence, according to administration officials.
The leaks targeting Ivanka Trump appeared to slow once Bannon departed the administration in August. Meanwhile, Trump and Kushner benefited from the structure under chief of staff John Kelly, who has helped West Wing staff to define their roles more clearly.
Bannon took aim at Ivanka publicly as recently as last month. Speaking at an election eve rally for Roy Moore, he appeared to mock her statement on Moore, criticizing members of his party who spoke out against the Senate candidate: "There's a special place in hell for Republicans who should know better."
And Bannon hasn't limited his criticism to the Washington-based members of the Trump family.
"They're going to crack Don Jr. like an egg on national TV," he told Wolff about the President's eldest son, according to excerpts obtained by The Guardian
The President's statement appeared to acknowledge that Bannon's leaks struck a nerve.
"Steve pretends to be at war with the media, which he calls the opposition party, yet he spent his time at the White House leaking false information to the media to make himself seem far more important than he was. It is the only thing he does well," Trump said.
For their part, Ivanka Trump and Jared Kushner, who spent the holidays with the President in Palm Beach, have kept their heads down, back at work in the West Wing and, through a spokesperson, declining to comment publicly on the unfolding scene.