And although he was a late addition to Team Trump, the president's former policy whisperer may still possess enough damning information to worry the White House and to intrigue special counsel Robert Mueller, who has reportedly subpoenaed Bannon to testify before a grand jury.
This creates potentially grave legal danger to the president, which is why Trump may refuse to be questioned by Mueller and make a full-blown constitutional crisis front page news around the world.
Fallen former President Trump confidante Steve Bannon will testify to lawmakers behind closed doors Tuesday in his first appearance on Capitol Hill since he ran afoul of the administration over quotes attributed to him in a bombshell book.
"Well, I certainly never said he cracked like an egg on TV", Murray's Bannon insists.
Bannon on Tuesday was appearing in a closed-door hearing with the House Intelligence Committee, which is also probing Russian interference in the election and whether any Trump campaign associates colluded.
Steve Bannon was subpoenaed for the second time in a week during testimony before a House panel on his time working for President Donald Trump.
Le'Veon Bell threatens retirement in 2018 if tagged again
I'm not going to settle for anything", Bell said. "I know what I do and what I bring to the table. Bell sat out virtually all of training camp this summer before returning to the team September 1.
If the public is going to get a real view of what's been said anytime soon, someone on the House side will have to pull a Feinstein.
Trump has denied wrongdoing, denounced the investigation as a witch hunt, and derided "Sloppy Steve" Bannon for discussing things he doesn't know anything about.
Trump's lawyers have served Bannon with a cease and desist letter claiming his statements in Fire and Fury constitute "defamation by libel and slander", and violate a non-disclosure agreement Bannon signed as a campaign employee.
A spokesman for Mr Mueller has declined to comment.
All this is joined by recent immigration measures by the head of the White House in recent days, such as the cancellation of the Temporary Protected Status (TPS) that saved the deportation until now to some 200,000 Salvadoran immigrants and their families.
He has since regretted the comments and has been fired from Breitbart News as part of the fallout. The controversy ensued following the release of a book that featured Bannon criticizing the president and two of his children.
"We can't do a thorough and credible investigation unless we talk to these witnesses and obtain these documents", Schiff said.