WASHINGTON _ Stephen K. Bannon helped guide Donald Trump to his upset victory in 2016, then became the president's chief strategist to help remake American politics from inside the White House.
Now, in the wake of an acrimonious falling out with Trump, Bannon will testify for the first time Tuesday to the House Intelligence Committee as it probes Russian interference in the U.S. presidential campaign, an investigation that has cast a long shadow on Trump's tenure.
Bannon's testimony, which he is delivering behind closed doors, has been hotly anticipated since this month's publication of "Fire and Fury," a book by Michael Wolff about Trump's first year in the White House.
Among other surprises, the book quotes Bannon denouncing a controversial meeting between a Kremlin-linked Russian lawyer and three top campaign officials at Trump Tower in June 2016 as "treasonous."
"Even if you thought that this was not treasonous, or unpatriotic, or bad ... and I happen to think it's all of that, you should have called the FBI immediately," Bannon is quoted as saying.
Bannon later said he was not aiming his barb at Donald Trump Jr., the president's eldest son, who arranged the meeting because he expected the Russians to provide damaging material on Hillary Clinton. Trump's son-in-law and adviser, Jared Kushner, and his campaign manager, Paul Manafort, also attended.
But Bannon's harsh comments destroyed what was left of his relationship with Trump, who said his former adviser "lost his mind" when he was forced out of the White House last August.
The fallout also cost Bannon his job running the right-wing website Breitbart News after his support from major political donors evaporated.
Given Bannon's eye-popping description of the Trump Tower meeting, the House Intelligence Committee will probably be interested in any more information about it. The meeting was hosted by Trump Jr. after a Russian lawyer promised damaging information about Clinton.
Trump Jr. later told Congress that no incriminating information was provided, and the conversation shifted to other topics.
Bannon's testimony also arrives at a contentious moment for the House Intelligence Committee. Rep. Adam Schiff of California, the panel's top Democrat, has repeatedly faulted his Republican colleagues for failing to allow a thorough investigation of the 2016 presidential campaign.
"We can't do a thorough and credible investigation unless we talk to these witnesses and obtain these documents," Schiff said.
Corey Lewandowski, Trump's former campaign manager, and Hope Hicks, the White House communications director, are also expected to testify in the coming days, according to a source who was not authorized to speak publicly and requested anonymity.
Committee Chairman Devin Nunes, R-Calif., was forced to step back from the Russia case during a controversy last year over how he handled classified information.
However, he's still aggressively pursued his own lines of inquiry examining whether the Department of Justice improperly investigated the Trump campaign.
