House Intelligence Committee Chairman Adam Schiff, D-Calif., said Sunday that House lawmakers have reached an agreement with the whistleblower who filed a complaint about President Trump’s July call with Ukrainian President Volodymyr Zelensky to testify before a congressional committee.

Speaking on ABC News' "This Week," Schiff said that the agreement with the whistleblower and his or her lawyers has been settled and that there are precautions being taken to protect the identity of the person amid the criticism from Trump and his allies.

"As with [acting Director of National Intelligence Joseph] Mcguire, that whistleblower will be allowed to come in without White House or DOJ lawyers to tell him or her what they can or can't say," Schiff said.

"We are taking all the precautions we can to protect the whistleblower's identity," Schiff added. "With President Trump's threats, you can imagine the security concerns here."

INTEL CHIEF DEFENDS HANDLING OF TRUMP CALL COMPLAINT, SPARS WITH SCHIFF IN TENSE HEARING

The whistleblower's complaint, with its detail and clear narrative, is likely to accelerate the impeachment process and put more pressure on Trump to rebut its core contentions and on his fellow Republicans to defend him or not. It also provides a road map for Democrats to seek corroborating witnesses and evidence , which will complicate the president’s efforts to characterize the findings as those of a lone partisan out to undermine him.

In response, Trump threatened “the person” who he said gave information to the whistleblower as he spoke at a private event in New York with staff from the U.S. mission to the United Nations.

“Who’s the person who gave the whistleblower the information? Because that’s close to a spy,” Trump said in audio posted by The Los Angeles Times. “You know what we used to do in the old days when we were smart? Right? The spies and treason, we used to handle it a little differently than we do now.”

Speaking on Sunday also on NBC News’ “Meet The Press,” Schiff said that the president’s behavior was so “egregious” that House lawmakers were forced to open an impeachment inquiry relating to his call with the Ukrainian leader.

“The gravamen of the offense here is the president using the power of his office to coerce a foreign nation into helping his presidential campaign to once again interfere in our election, and at the same time withholding foreign aid that country so desperately needs to fight off who? The Russians,” Schiff said.

He added: “The situation demands that we move forward with the inquiry.”

On Tuesday, House Speaker Nancy Pelosi formally announced an impeachment inquiry into Trump over his July 25 phone call with Zelensky. Democrats have claimed the president threatened to withhold $400 million in military aid unless Ukraine investigated former Vice President Joe Biden, his son Hunter, and their business dealings in the country.

The probe was prompted by a complaint from an intelligence community whistleblower who accused Trump of "using the power of his office to solicit interference from a foreign country in the 2020 U.S. election."

Pelosi specifically charged that the administration had violated the law by not turning over a whistleblower complaint concerning Trump's July call with Zelensky. Citing testimony that the director of national intelligence was blocking the release of that complaint, she said: "This is a violation of law. The law is unequivocal."

Trump had urged Zelensky to investigate former Vice President Joe Biden and his son Hunter. Joe Biden has acknowledged on camera that, when he was vice president, he successfully pressured Ukraine to fire its top prosecutor, Viktor Shokin, who was investigating the natural gas firm Burisma Holdings — where Hunter Biden was on the board. Shokin himself had been separately and widely accused of corruption.

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Schiff on Sunday said that while he expects the White House to push back on the House’s attempts to ascertain information regarding the president’s actions, any attempts to thwart the investigation would be viewed as obstruction.

"The president can't have it both ways — he can't both prevent us from getting evidence on these serious underlying crimes, or potential crimes, this serious breach of his oath of office, and at the same time obstruct our investigation," he said. “Even as he tries to weaken our ability to get facts on one, he’s going to strengthen the facts on the other."

The Associated Press contributed to this report.