A senior member of a key House Intelligence panel says he's "surprised" and "taken aback" by the confrontational response from CIA Director John Brennan to allegations that his agency spied on a Senate committee.

Rep. Adam Schiff Adam Bennett SchiffTop Democrats call for DOJ watchdog to probe Barr over possible 2020 election influence Overnight Defense: Top admiral says 'no condition' where US should conduct nuclear test 'at this time' | Intelligence chief says Congress will get some in-person election security briefings Overnight Defense: House to vote on military justice bill spurred by Vanessa Guillén death | Biden courts veterans after Trump's military controversies MORE (D-Calif.), a member of the House Permanent Select Committee on Intelligence, said Sen. Dianne Feinstein Dianne Emiel FeinsteinMcConnell says Trump nominee to replace Ginsburg will get Senate vote Top Democrats call for DOJ watchdog to probe Barr over possible 2020 election influence Intensifying natural disasters do little to move needle on climate efforts MORE's (D-Calif.) spying charges are "very serious" and warned that Brennan's aggressive reaction risks undermining the relationship between Congress and the CIA.

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"I can understand, as a relatively new director, his wanting to go to bat to support his agency. But I don't think a confrontation with the Senate is in either his interest or the interest of the agency," Schiff said Friday during taping of C-Span's "Newsmakers" program, which will air Sunday. "So I've been a little bit taken back by the degree to which they have, you know, really kind of pushed back without any kind of conciliation on this."

While Schiff described his own interactions with Brennan as "very positive," he was quick to add that the CIA chief should be more cooperative with the congressional offices investigating the CIA's advanced interrogation methods under the Bush administration.

"His first response should have been – if indeed they accessed these computers without going to the senators first … – that, 'We made a mistake. We have concerns we need to explore with you but we should have done this … in an above-board fashion working with you, not working against you.'

"So it's not how I would have handled it," Schiff added, "and I think it does raise some legitimate concerns."

Schiff has joined a growing chorus of lawmakers who are questioning, not only the CIA's conduct surrounding the Senate Intelligence Committee's investigation, but Brennan's response to the allegations from Feinstein, whose historic defense of the CIA has only added force to her charges.

"I have grave concerns that the CIA search may well have violated the separation of powers principles," Feinstein, who heads the Intelligence Committee, said Tuesday in a surprise speech on the Senate floor. "I am not taking it lightly."

Brennan was quick to deny the allegations, telling NBC News that the CIA was "in no way" spying on the Senate.

“We greatly respect the separation of power between the executive branch and the legislative branch,” Brennan said.

The back-and-forth marks a sharp escalation of tensions between the CIA and the Senate panel that oversees it.

The Intelligence Committee has compiled a yet-unreleased report that's said to be highly critical of the CIA's interrogation programs under the Bush White House.

House Minority Leader Nancy Pelosi (D-Calif.) joined the debate earlier in the week, when she praised Feinstein's "courage" for taking on the CIA and took a shot at Brennan's response.

"I haven't really seen much of … Director Brennan's statements on this, but what I have seen, are befuddling to me," Pelosi told reporters Thursday. "From what Sen. [Feinstein] said and what you have written, it's pretty appalling what is being alleged."

Some civil liberties groups have accused Feinstein and others in Congress of hypocrisy for defending the government's spying programs when they were aimed at civilians, but attacking them when they themselves became the alleged targets.

Schiff dismissed that argument Friday, saying that while it has "a certain intellectual appeal," it ignores a long list of nuanced considerations – including the separation of powers, the Constitution's speech-and-debate clause and statutes related to electronic communications and executive orders – that set the two situations apart.

"There are a raft of additional considerations," Schiff said. "It doesn't mean necessarily they're more weighty than the individual privacy rights and Fourth Amendment concerns of lay people, but it does add yet another layer to this debate.

"I understand the criticism, and it's an attractive one," he added. "But as many of us have been pushing for reform, I don't think it's a fair one."

The "Newsmakers" program will air on Sunday at 10 a.m. and again at 6 p.m.