Updated Monday at 9:35 a.m. ET
House Speaker Nancy Pelosi issued a stern warning for President Trump on Sunday: Do not try to retaliate against the intelligence community official whose anonymous complaint helped spur the impeachment inquiry.
"I will make sure he does not intimidate the whistleblower," Pelosi said in an interview on CBS' Face the Nation. "I told the president, you're in my wheelhouse when you come after the whistleblower."
Pelosi's comments follow Trump's repeated calls for the whistleblower's name to be exposed. Trump claimed on Friday that "everybody knows" who the whistleblower is, calling the person's identity "no great secret."
But it is not clear that Trump truly knows who filed a complaint about his July 25 call with the president of Ukraine in which he pressed for the country to open investigations into the Biden family and a disproven theory about 2016 election meddling by Ukraine. The whistleblower wrote that Trump's actions raised national security concerns and constituted an abuse of power.
Trump and some of his Republican supporters have ramped up their attacks on the whistleblower's credibility as House impeachment investigators continue to call witnesses to testify for nationally televised hearings into the president's conduct.
Lawyers representing the whistleblower say respecting the individual's anonymity is important to their client's safety, as well as ensuring that future whistleblowers will not have to fear intimidation in response to reporting government abuse. Pelosi told CBS that the process that allows whistleblowers to come forward anonymously should not be undermined.
"This is really important, especially when it comes to intelligence, that someone who would be courageous enough to point out truth to power," she said.
Federal law allows the whistleblower to remain anonymous, but it is not expressly a crime for the president to unmask the person. Legal experts have said that if Trump outs the individual, it could prompt an article of impeachment.
Pelosi did not elaborate on what exactly the House's response would be if Trump decides to do so.
Conservative media have named someone thought to be the whistleblower and attempted to portray the person as a political enemy of the president. But the reports are speculative, since there has been no official confirmation of the whistleblower's identity.
The whistleblower's legal team has sent a cease and desist letter to the White House counsel, warning that the president should stop calling for the whistleblower to be publicly revealed.
"Let me be clear: Should any harm befall any suspected named whistleblower or their family, the blame will rest squarely with your client," wrote attorney Andrew Bakaj.
House Democrats say the person's testimony is no longer integral to the impeachment investigation since the whistleblower's complaint has been largely corroborated by other witnesses.
Democrats say Trump tried to bribe the president of Ukraine, Volodymyr Zelenskiy, by conditioning $391 million in military assistance that was already approved by Congress on Ukraine announcing investigations that would politically benefit Trump. The White House released the aid after Congress learned about the whistleblower complaint.
Republicans appearing on Sunday talk shows argued that since the money was eventually delivered to Ukraine without the country launching political investigations, there was nothing wrong with the now infamous July 25 phone call.
"Most importantly, the Ukrainians did nothing to, as far as investigations goes, to get the aid release," Rep. Jim Jordan, R-Ohio, said on CBS. "So there was never this quid pro quo that the Democrats all promise existed before President Trump released the phone call."
Eight witnesses are expected to testify this week, including Lt. Col. Alexander Vindman, the top Ukraine expert at the National Security Council, and Gordon Sondland, the U.S. ambassador to the European Union.
Vindman, a key witness in the inquiry, was listening in on Trump's July 25 call and in closed-door testimony said he was so alarmed by the president's behavior that he rushed to report it to John Eisenberg, the top lawyer for the NSC.
Sondland is also an important player in the impeachment probe. In a sharp reversal, Sondland earlier this month submitted an addendum to his original closed-door testimony to House lawmakers acknowledging that he now does recall informing an aide to Zelenskiy that military aid to Ukraine was linked to the announcement of "anti-corruption" investigations.
House lawmakers on Saturday released a transcript of closed-door testimony from National Security Council official Tim Morrison.
Morrison said Sondland told a Ukrainian official that U.S. assistance would be sent to Kyiv once investigations were announced. In his testimony, Morrison said Sondland spoke directly to Trump about the arrangement about half a dozen times.
Pelosi on Sunday said if Trump wants to defend himself, he has an open invitation to speak to House investigators.
"The president could come right before the committee and talk, speak all the truth that he wants if he wants — if he wants to take the oath of office or he could do it in writing," she said. "He has every opportunity to present his case."
On Monday, Trump indicated that he may take Pelosi up on the invitation to provide testimony to impeachment investigators — at least in writing.
"I like the idea & will, in order to get Congress focused again, strongly consider it!" the president tweeted.