Speaker of the House Nancy Pelosi (D-CA) walks to a government vehicle after speaking at an American Federation of Government Employees labor union rally at the U.S. Capitol in Washington, U.S., September 24, 2019.

House Speaker Nancy Pelosi cautioned Thursday against rushing to impeach President Donald Trump even as she said the president "betrayed" his oath of office.

Speaking to reporters, the California Democrat responded to a newly public whistleblower complaint alleging Trump abused his power by asking Ukraine's president to investigate the family of former Vice President Joe Biden, one of his chief rivals for the presidency in 2020. The document also detailed alleged White House efforts to "lock down" records of Trump's July call with Ukrainian President Volodymyr Zelensky.

"This is a cover-up," Pelosi said after outlining the accusations in the complaint.

The speaker, aiming to balance the concerns of liberals who have long agitated to remove Trump from office and centrists from swing districts who only this week backed action on impeachment, stressed that she wants a patient investigation into Trump's conduct. She also aimed to show that House Democrats will still make policy despite their decision this week to start an impeachment inquiry, as Trump and his allies accuse the party of a politically motivated probe ahead of the 2020 election.

Pelosi did not commit to timing on drafting or voting on articles of impeachment, which effectively constitute charges against the president. She said House committee investigations will determine the timing of the proceedings.

"There are some in our caucus who think, 'let's just have an impeachment.' ... There is no rush to judgment," Pelosi said.

She also contended the Office of the Director of National Intelligence "broke the law" by not immediately passing the August whistleblower complaint to congressional intelligence committees. Asked about the delay during a House Intelligence Committee hearing Thursday, acting Director of National Intelligence Joseph Maguire called the situation "unprecedented" and said it seemed "prudent to be able to check and ensure" before he sent the complaint to Congress.

The Trump administration gave the document to Congress only Wednesday as it faced pressure created by growing support for impeachment.

Pelosi added that her party reached a consensus that it would focus on "this allegation" related to Ukraine. Some House members have called for impeachment based on other accusations, such as those that Trump obstructed special counsel Robert Mueller's Russia investigation or profits from the presidency through his private businesses.

Currently, 219 House Democrats and one independent support some action on impeachment, according to NBC News. The group constitutes a majority of House members and nearly all of the 235 Democrats in the chamber.

Trump has repeatedly characterized his call with Zelensky as "perfect."

In a statement Thursday, White House press secretary Stephanie Grisham said, "Nothing has changed with the release of this complaint, which is nothing more than a collection of third-hand accounts of events and cobbled-together press clippings—all of which shows nothing improper." She said the president released a memorandum summarizing the call Wednesday "because he has nothing to hide."

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