UPDATE:

After months of pushing off demands from her Democratic colleagues and the U.S. public, Speaker of the House Nancy Pelosi on Tuesday announced her support for an official impeachment inquiry into President Donald Trump.

In a televised press conference following a closed-door caucus meeting, Pelosi said the "actions taken to date by the president have seriously violated the Constitution—especially when the president says, 'Article II says I can do whatever I want.' For the past several months we have been investigating in our committees and litigating in the courts so the House can gather all the relevant facts and consider whether to exercise its full Article I powers, including a constitutional power of the utmost gravity — approval of articles of impeachment."

Citing the president's own admission about what he asked of the Ukrainian president during a phone call earlier this year—the contents of which only came to light last week following a whistleblower complaint from inside the nation's intelligence community—Pelosi said it "revealed the dishonorable fact of the president's betrayal of his oath of office, betrayal of our national security, and betrayal of the integrity of our elections."

"Therefore today," Pelosi continued, "I'm announcing the U.S. House of Representatives is moving forward with an official impeachment inquiry. The president must be held accountable. Nobody is above the law."

Watch a portion of Pelosi's remarks:

.@SpeakerPelosi announces: "The actions of the Trump Presidency revealed... betrayal of his oath of office... our nat'l security... and the integrity of our elections. Therefore... the House is moving forward with an official impeachment inquiry" - WATCH: https://t.co/JJL99jfIBm pic.twitter.com/AZ2XBjENd9 — CSPAN (@cspan) September 24, 2019 -

Following her remarks, Pelosi did not take questions from the reporters gathered.

Earlier (3:33pm ET): Pelosi Reportedly Set to Announce Official Trump Impeachment Inquiry

House Speaker Nancy Pelosi reportedly plans to announce Tuesday a formal impeachment inquiry into President Donald Trump after a flood of pressure from the Democratic caucus and the American public forced her hand.

The Washington Post reported Tuesday afternoon that Pelosi will publicly support an impeachment probe in an address to the media following a closed-door House Democratic caucus meeting.

The announcement is expected to come after more than a dozen House Democrats expressed support for impeachment in less than 24 hours. According to an Axios tally, a total of 164 House Democrats support launching an impeachment inquiry.

"The dam's not breaking. It's broken," Rep. David Cicilline (D-R.I.) tweeted Tuesday. "Proud that so many of my colleagues are standing up to President Trump's wanton abuse of power today. It is clear that there is no other option than to impeach this president."

Pelosi has long opposed launching impeachment proceedings against the president, but the Speaker is reportedly crumbling under pressure from her caucus following reports that Trump pushed Ukraine's leader to investigate former Vice President Joe Biden.

"Pelosi has told friends that impeachment now feels unavoidable," Axios reported, citing Democratic aides. "She hates the politics of it, but has succumbed to the inevitability."

The reports that Pelosi is set to announce a formal impeachment probe came after Trump authorized the release of an unredacted transcript of his July 25 phone conversation with Ukrainian President Volodymyr Zelensky.

According to the Post, Pelosi and top House Democrats "have been privately discussing the creation of a select committee to conduct the possible impeachment of Trump."

"The California Democrat has spoken to key allies in recent days about establishing a special panel rather than leaving the task with the House Judiciary Committee," the Post reported. "Nothing has been decided... but some members are expected to publicly endorse the move soon."

Some progressives and House Democrats expressed concerns about establishing a select committee, warning the move could further delay the impeachment process.

Rep. Alexandria Ocasio-Cortez (D-N.Y.) tweeted Tuesday that the House doesn't "have the luxury of time with another committee."

"Judiciary has been investigating and putting the pieces together for months," said Ocasio-Cortez. "Impeachment belongs there."

Anna Galland, executive director of MoveOn Civic Action, agreed with the New York Democrat, tweeting "there's just no time for delay."

"A select committee would delay us further and wouldn't unearth any more information," said Galland. "The Judiciary Committee should move immediately on articles of impeachment."

While a slew of previously reluctant lawmakers have joined the call for impeachment over the last several days, outside advocacy groups like Indivisible called on constituents to make sure their representatives have heard from them:

There are still many Democrats who refuse to take a stand against Trump’s blatant corruption, is your Member of Congress one of them? Make a call now. there are still many Democrats who refuse to take a stand against Trump’s blatant corruption.https://t.co/XzqxgaNaTP — Indivisible Guide (@IndivisibleTeam) September 24, 2019

"Calls are the most impactful thing right now," the group said, "because House Democrats are going to set direction on this in the next 24 hours or less and they need to hear from us right away."