The newly launched impeachment inquiry against President Trump will touch off a rapid-fire sequence of potentially momentous developments Wednesday, as the White House aims to neutralize the threat and gain the upper hand in a political tempest whose outcome is far from settled.

The president kicked off the day with an early-morning tweet decrying the probe: “There has been no President in the history of our Country who has been treated so badly as I have. The Democrats are frozen with hatred and fear. They get nothing done. This should never be allowed to happen to another President. Witch Hunt!”

This came after House Speaker Nancy Pelosi, D-Calif., on Tuesday answered mounting impeachment calls in her caucus by announcing a formal impeachment inquiry. Pelosi’s move came after months of reluctance to press forward on that front out of concern about the political implications for her party. But Tuesday, amid new allegations surrounding a now-controversial phone call between Trump and Ukrainian President Volodymyr Zelensky in July, she endorsed the process. Trump is under fire for allegedly pressuring Ukraine's leader to investigate Joe Biden and his son, Hunter, and using military aid as leverage -- though the president denies the latter charge.

PELOSI ANNOUNCES FORMAL IMPEACHMENT INQUIRY AGAINST TRUMP

“The president must be held accountable,” Pelosi said, citing his alleged “betrayal of his oath of office, betrayal of our national security, and the betrayal of the integrity of our elections.”

Pelosi and Democrats also allege that the administration violated the law by not turning over a whistleblower complaint concerning Trump’s July call.

That complaint may soon be turned over, however, as the administration weighs how to handle the document. Further, the White House is planning to release the transcript of the call itself on Wednesday. Justice Department lawyers, as well as lawyers at the White House, have been advising White House officials to release the transcript since last week, a source familiar with the conversations told Fox News.

Whether that transcript hurts or bolsters the president's case remains to be seen. But he will have many opportunities to shape the narrative as the day plays out.

Later, Trump is slated to meet with Zelensky, in what will be a high-stakes moment amid the impeachment push, on the sidelines of the United Nations General Assembly in New York. The meeting was previously scheduled, unrelated to the whistleblower allegation, though the two leaders are expected to receive questions from reporters on the matter.

Trump then is expected to hold a press conference in New York in the late afternoon, where the impeachment drive is sure to be front and center.

The White House also is expected to release a document that shows the intelligence community inspector general found that the whistleblower who first leveled the explosive allegation against Trump had “political bias” in favor of a “rival candidate” of the president. Fox News previously reported that, according to a source, the individual also did not have “firsthand knowledge” of the phone call.

A senior Trump administration official told Fox News that the White House has been working as quickly as it can to release to Congress the whistleblower complaint involving Trump’s conversations with the Ukrainian president, as long as it’s legally possible.

The White House has maintained that they have nothing to hide and that there has been no wrongdoing. Their general position has been that it will make everything possible available to Congress or the public regarding Trump’s call and the complaint to the intelligence community’s inspector general.

Meanwhile, on Capitol Hill, the agenda is no less packed.

WH TO RELEASE DOCUMENT SHOWING INTEL COMMUNITY IG FOUND WHISTLEBLOWER HAD 'POLITICAL BIAS', SOURCE SAYS

House Democratic and GOP leaders are expected to hold press conferences following their respective closed caucus meetings. Republicans will likely paint Pelosi’s impeachment inquiry announcement as noise, while Democrats will cast it as a significant escalation in the process.

A Democratic source told Fox News late Tuesday that Pelosi’s formal inquiry takes the Trump-focused investigations being run by six separate House committees and puts them “under one umbrella.” The committees involved are House Judiciary, Intelligence, Foreign Affairs, Financial Services, Oversight, and Ways and Means.

The source told Fox News that because the “impetus” leading up to her announcement was focused on Ukraine, House Intelligence Committee Chairman Adam Schiff, D-Calif., will have a “heavy role” in how the process unfolds.

CLICK HERE TO GET THE FOX NEWS APP

At some point in the day, the House will vote on a resolution on the handover of the whistleblower complaint to the House Intelligence Committee.

Negotiations are still ongoing over whether the whistleblower will testify or appear before Congress in any way. Schiff on Tuesday night requested a voluntary interview with the whistleblower for Thursday—following the public testimony of Acting Director of National Intelligence Joseph McGuire on Thursday morning.

Fox News' John Roberts, Ed Henry, Gregg Re, and Chad Pergram contributed to this report.