WASHINGTON (ABC News) – House Speaker Nancy Pelosi announced on Tuesday that Democrats were moving forward with an official impeachment inquiry into President Donald Trump.

“The actions of the Trump presidency 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,” Pelosi said. “Therefore, today I’m announcing the House of Representatives is moving forward with an official impeachment inquiry.”

Just hours earlier, President Trump promised to release an unredacted transcript of his phone call with Ukraine’s president in July that has triggered a new Democratic push for impeachment

Just hours earlier, President Trump promised to release an unredacted transcript of his phone call with Ukraine’s president in July that has triggered a new Democratic push for impeachment

Trump tweeted that the transcript, which he said would be made public Wednesday, would show that it was “a totally appropriate call.”

“NO quid pro quo!” he said.

The fast-moving developments came amid new questions about whether Trump had made aid to Ukraine contingent on Ukraine’s President Volodymyr Zelensky agreeing to investigate former Vice President Joe Biden and his son, Hunter.

Trump, who had said previously he was concerned about sending aid to Ukraine because of corruption he alleged there, gave a new explanation Tuesday, saying he had ordered the aid frozen — before the call — because he was unhappy with how much European countries were contributing to Ukraine.

Also Tuesday afternoon, the Democratic chairman of the House Intelligence Committee tweeted that the whistleblower who filed a formal complaint about Trump’s call wanted to talk to his committee.

Over the past 24 hours a rapid succession of Democrats embracing impeachment has pushed Pelosi and her caucus to the brink of going forward on the matter.

The Pelosi announcement was scheduled after all Democrats were scheduled to meet Tuesday afternoon and at least 166 Democrats — more than two-thirds of the caucus – now publicly supporting impeaching President Donald Trump.

At the same time, House Democrats were drafting a resolution to pressure the Director of National Intelligence to release a whistleblower complaint to Congress. The measure will be on the floor for consideration on Wednesday, according to a senior Democratic leadership aide.

During a live interview at The Atlantic Festival Tuesday afternoon, Pelosi said, “This isn’t about politics. If we have to honor our oath of office to support and defend the Constitution of the United States, from all enemies, foreign and domestic, that’s what we’re have to do.

“We have to have the facts. That’s why I’ve said, soon as we have the facts, we’re ready. Now we have the facts. We’re ready. For later today. But — but so this isn’t about politics,” she said.

Biden, on the campaign trail in Wilmington, Delaware, said, “If the president does not comply such a request of the Congress, if he continues to obstruct Congress and flaunt the law, Donald Trump will leave Congress in my view no choice but to initiate impeachment.”

Democratic sources familiar with Pelosi’s deliberations tell ABC News one option under consideration is forming a select committee to handle impeachment and a potential investigation into the new national security whistleblower complaint over the Trump call. The select committee would be separate from the House Judiciary Committee inquiry into whether Trump committed obstruction if justice.

It’s unclear what jurisdiction the committee would have over the issue, and whether it would be to investigate the Ukraine matter or impeachment more broadly. It’s also not clear who would lead it, but Schiff has had his name floated as a possibility. Schiff is a true Pelosi loyalist and if he were at the helm it would allow her to exert some additional control over the committee. It could also create new logistical challenges, and ruffle feathers of other committee leaders – and be seen as another sign of the frustration within the caucus with the way House Judiciary Chairman Jerry Nadler has handled the investigation so far.

Creating a select committee could lead to impeachment, but that is not a foregone conclusion. It would, however, be a sign that Democrats are inching closer to it and that Pelosi is moving more aggressively, even as some of the most politically vulnerable Democrats she’s been protecting have come out for impeachment, giving her political cover to move ahead.

Pelosi will huddle this afternoon with her leadership team, the chairmen of six committees investigating the president and will hold a special caucus meeting to discuss impeachment.

Arriving at the Capitol Tuesday morning, Pelosi ignored a question asking whether it is time to impeach the president now that more than 150 Democrats are now out for impeachment.

Seven freshmen Democrats, all veterans of the military, defense and intelligence agencies, wrote an op-ed in the Washington Post Monday evening calling allegations that the president pressured Ukraine to investigate Democratic presidential frontrunner Joe Biden, “a direct violation of our national security.”

At the United Nations Tuesday, Trump insisted he had done nothing improper and called the new impeachment talk “ridiculous and a “witch hunt.”

“If these allegations are true, we believe these actions represent an impeachable offense,” Reps. Gil Cisneros, Jason Crow, Chrissy Houlahan, Mikie Sherrill, Elissa Slotkin, Abigail Spanberger, and Elaine Luria,” wrote collectively. “We do not arrive at this conclusion lightly, and we call on our colleagues in Congress to consider the use of all congressional authorities available to us, including the power of “inherent contempt” and impeachment hearings, to address these new allegations, find the truth and protect our national security.”

Amid the whistleblower complaint, some of Pelosi’s closest allies have also recently cut off their patience regarding impeachment, perhaps affording Pelosi with political cover and ending the prolonged defense of slow-walk the process through a thorough, methodical investigation.

Connecticut Democratic Rep. Rosa DeLauro called the complaint a “matter of grave urgency.”

“As with many of my colleagues, I have been reluctant to call for an impeachment inquiry because it would further divide the country, be perceived as overturning the 2016 election, and go to the United States Senate where Republicans would acquit President Trump regardless of the evidence. But these actions regarding the 2020 election are a turning point,” DeLauro wrote in a statement. “An impeachment inquiry may be the only recourse Congress has if the President is enlisting foreign assistance in the 2020 election. Congress must meet this pivotal moment in our nation’s history with decisive action.”

Meanwhile, Republicans are digging into their defense of the president, with Texas Republican Rep. Lance Gooden introducing a resolution to remove Nadler from his chairmanship.

“By law, [Nadler] may not launch impeachment proceedings until the full House votes for him to do so,” Gooden asserted. “This attempted coup against a duly-elected, sitting president is unprecedented and must be stopped. I urge the Majority to move immediately to have him stripped of his chairmanship and that any accomplices on the Judiciary Committee not be considered as a replacement.”