Stephen Bannon, President Donald Trump's former chief strategist, was subpoenaed last week by special counsel Robert Mueller to testify before a grand jury as part of the investigation into possible links between Trump's associates and Russian Federation, according to a person with direct knowledge of the matter.
Mr Bannon, a champion of Mr Trump's "America First" agenda, was among the Republican's closest aides during the 2016 election campaign, the presidential transition and his first months in office.
It's unclear who Burck communicated with or whether it was top White House lawyer Don McGahn.
After the book's publication, Bannon expressed regret about his statements and called Trump Jr.
Mr Bannon spent hours on Tuesday meeting behind closed doors with members of the House of Representatives Intelligence Committee.
Moreover, Schiff said Lewandowski would not answer questions about "meetings [or] conversations" that took place after Trump fired him from the campaign in June 2016, saying he was unprepared to answer but would come back to do so.
A spokeswoman for Bannon did not respond to multiple requests for comment.
A spokesman for Mr Mueller's office declined comment. Uttam Dhillon, the White House lawyer responsible for responding to congressional investigators in the Russian Federation probe, had made the executive privilege request to Bannon's lawyer, William Burck, before Bannon's appearance Tuesday, according to a person familiar with the matter.
Bannon is expected to be interviewed by prosecutors instead of testifying before a grand jury.
That's according to people familiar with the closed-door session who spoke to The Associated Press on condition of anonymity because they were not authorized to speak publicly. He also refused to discuss conversations he may have had with Trump after he left the White House.
He realized immediately after that he had slipped up, because the White House told Bannon not to answer questions related to his work on the presidential transition team or in the White House.
"The scope of this assertion of privilege, if that's what it is, is breathtaking".
It emerged later that the White House had instructed Bannon not to talk about anything other than the campaign, even after the subpoena. "So this obviously can't stand".
"I certainly think that the committee respects executive privilege", Mr. Rooney said, but said the question was at what point does the privilege kick in for someone like. "It's not Mr. Bannon's right to waive it".
"As with all congressional inquiries touching upon the White House, Congress must consult with the White House prior to obtaining confidential material", Sanders said.
Bannon divulged the details while he was testifying before the House Intelligence Committee on Tuesday.
It was clear by Tuesday night that Bannon had invoked a "remarkably broad definition of executive privilege", as one congressman put it, during the interview.
Senior committee Republican, Rep. Tom Rooney of Florida, told reporters that the issue of executive privilege was "dominating the day".
Lewandowski was sacked as campaign manager on June 20, 2016, and replaced by Paul Manafort, who has been indicted on money-laundering charges by Special Counsel Robert Mueller.