House Intelligence Committee Chairman 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.) said Sunday that the U.S. intelligence community is beginning to withhold documents on Ukraine from Congress as lawmakers prepare for the impeachment trial of President Trump Donald John TrumpObama calls on Senate not to fill Ginsburg's vacancy until after election Planned Parenthood: 'The fate of our rights' depends on Ginsburg replacement Progressive group to spend M in ad campaign on Supreme Court vacancy MORE.

"They appear to be succumbing to pressure from the administration," Schiff said on ABC's "This Week."

"The NSA, in particular, is withholding what are potentially relevant documents to our oversight responsibilities on Ukraine but also withholding documents potentially relevant that the senators might want to see during the trial," he added, referring to the National Security Agency.

The California congressman made the comments after being questioned about a Politico report that said intelligence officials were pushing House and Senate Intelligence committees to forgo the public portion of an annual briefing on world security threats.

The request was reportedly made in an effort to avoid the prospect of top officials publicly disagreeing with Trump on matters related to Iran, Russia and North Korea.

"Unfortunately, I think those reports are all too accurate," Schiff said. "The intelligence community is reluctant to have an open hearing, something that we had done every year prior to the Trump administration, because they're worried about angering the president."

The NSA referred The Hill to the Office of the Director of National Intelligence (ODNI) when reached for comment. "The Intelligence Community is committed to providing Congress with the information and intelligence it needs to carry out its critical oversight role," Amanda J. Schoch, a spokeswoman for ODNI, said in a statement. "The IC is working in good faith with [the House Intelligence Committee] to respond to requests on a broad range of topics and will continue to do so."

Schiff emerged as a focal figure in the House Democrats' impeachment inquiry into allegations about Trump's dealings with Ukraine. Trump is accused of pressuring Ukraine to announce politically beneficial investigations and using nearly $400 million in military aid as a source of leverage in his push for the probes.

The House in December voted to impeach Trump for abuse of power and obstruction of Congress, making Trump just the third president in U.S. history to face Senate removal.

Schiff said on ABC that the facts surrounding the case aren't "seriously contested" and argued that the White House's defense supported his position.

"The only thing really new about the president's defense is that they're now arguing, I think, because they can't contest the facts, that the president cannot be impeached for abusing the power of his office," Schiff said.