House Speaker Nancy Pelosi said she told President Donald Trump that he's in her "wheelhouse" when he attacks the whistleblower, whose complaint initially prompted the House impeachment inquiry of the President.

"I will make sure he does not intimidate the whistleblower. I was there. I told the President you're in my wheelhouse when you come after the whistleblower," Pelosi said in part of a CBS News interview released Saturday.

Trump has repeatedly attacked and tried to discredit the whistleblower, and has made false claims about the individual on Twitter and at his rallies. A lawyer for the whistleblower sent a letter to the White House warning the President to "cease and desist" attacking his client.

"This is really important, especially when it comes to intelligence, that someone who would be courageous enough to point out truth to power and then through the filter of a Trump appointed inspector general who found it of urgent concern and ... then took it to the next steps," Pelosi said.

Pelosi said Trump has "every opportunity to present his case" before Congress, and could "take the oath of office or he could do it in writing."

The House speaker said Trump's actions are "so much worse" than those of former President Richard Nixon, who faced impeachment amid the Watergate scandal but resigned before the House of Representatives could take a vote.

"But it's really a sad thing," Pelosi continued. "I mean, what the President did was so much worse than even what Richard Nixon did, that at some point Richard Nixon cared about the country enough to recognize that this could not continue."

The whistleblower's complaint alleges Trump abused his official powers "to solicit interference" from Ukraine in the 2020 election and that the White House took steps to cover it up. Trump has denied any wrongdoing.

A rough transcript released by the White House shows Trump repeatedly pushed Ukrainian President Volodymyr Zelensky to investigate former Vice President Joe Biden, Trump's potential 2020 political rival, and his son Hunter Biden. There is no evidence of wrongdoing by Joe or Hunter Biden.

Pelosi on Sunday said she has "no idea" if the impeachment inquiry will be completed by the end of the year, despite a fast-moving timeline that suggests otherwise.

"I have no idea," Pelosi said in the CBS interview that aired Sunday. "No, I mean, it is self-evident that we have open hearings for the next week. I don't know if there are any beyond that. Then we're out for Thanksgiving. Doesn't mean depositions couldn't be taken during that time. And then when we come back by then, maybe a decision or maybe they have more hearings. And then I have six committees who have been working on all of this, and those six chairmen have been very involved in what the, how we will proceed."

Her comments come after the first week of public hearings and continued closed-door depositions in the widening impeachment investigation. More hearings and depositions are set to take place this week. As CNN has previously reported, House Democrats have shown they are rapidly moving to complete the proceedings by Christmas, something that could result in Trump being just the third president to be impeached in history.

This story has been updated with additional developments Sunday.

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