President Donald Trump cycled through a range of conflicting reactions Tuesday as Democrats moved swiftly toward concrete congressional action on impeachment.

The president moved from dismissing the renewed push by Democrats for impeachment proceedings early in the day to bemoaning the effort's impact while holding meetings with world leaders at the United Nations just a few hours later, to expressing social media outrage over "PRESIDENTIAL HARASSMENT!" as evening fell.

"Pelosi, Nadler, Schiff and, of course, Maxine Waters! Can you believe this?" he asked in a late afternoon tweetstorm shortly after House Speaker Nancy Pelosi announced the launch of a formal impeachment inquiry. By Wednesday morning, Trump lamented on Twitter that 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," he continued, additionally calling the new impeachment push a "Witch Hunt!"

Meanwhile, the day's impeachment developments were being met inside his inner circle with a mix of trepidation and defiance, as the president and his allies entered what they acknowledged was uncharted territory, according to multiple sources familiar with their thinking.

Pelosi's move followed growing outrage among Democrats at Trump's reported pressure on Ukraine's president to investigate 2020 rival Joe Biden while that country was awaiting U.S. aid he'd delayed, including a request during a summer phone call between the two leaders.

Early Tuesday, Trump dismissed the Democratic outrage as partisan posturing. “I think it’s a ridiculous witch hunt,” Trump said ahead of his morning remarks at the United Nations General Assembly in New York, reviving some of the same pushback he used during former special counsel Robert Mueller’s Russia investigation. “I’m leading in the polls. The only way they can stop me is impeachment.”

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As news broke later in the day that Pelosi planned to announce a formal impeachment inquiry, Trump said that he would release a transcript Wednesday morning.

"You will see it was a very friendly and totally appropriate call," he tweeted. "...This is nothing more than a continuation of the Greatest and most Destructive Witch Hunt of all time!"

Democrats have called for the full release of a complaint by an intelligence community whistleblower that is said to include, but not be limited to, that call. A senior administration official said the White House was preparing to turn over the whistleblower complaint by this Thursday.

Rep. Adam Schiff, D-Calif., who heads the House Intelligence Committee, said a lawyer for the whistleblower had contacted his committee saying they would like to testify, and that the panel has requested guidance from the acting Director of National Intelligence on how to move forward.

Later Tuesday afternoon, ahead of a meeting by Democratic lawmakers on Capitol Hill to discuss potential action, the president accused the party of failing to take action on a range of issues, including gun safety, due to presidential investigations. “So bad for our Country!” he tweeted.

(The Democratic House has passed several gun safety measures; the GOP Senate is waiting for the president to indicate his preferred policy solutions on the issue before taking action in the wake of several mass shootings this summer.)

Then, during a meeting with the Iraqi president, he ran through a list of U.S. economic indicators, saying "the country’s doing the best it’s ever done, and I just heard that [Pelosi would] like to impeach."

"...If she does that, they all say that’s a positive for me in the election," he said. "You could also say: who needs it, it’s bad for the country.”

Trump's damage control efforts on the domestic front Tuesday came as he looked to make his mark on the world stage, making a speech to the United Nations General Assembly and holding a string of meetings with world leaders.

"Such an important day at the United Nations," he tweeted Tuesday afternoon, moments after Pelosi's announcement. "So much work and so much success, and the Democrats purposely had to ruin and demean it with more breaking news Witch Hunt garbage. So bad for our Country!"

Full coverage: Trump impeachment inquiry

While Democrats have spent the last two years calling for various lines of impeachment, Pelosi is now triggering an official process that could translate to months of hearings, subpoenas and witness testimony — and, potentially, both new revelations and the passage of articles of impeachment as the president battles for re-election.

There is no indication yet that Trump could be removed from office, which would require a two-thirds vote from the Republican-led Senate.

More than two-thirds of House Democrats now back some type of impeachment action — still not enough to claim the simple House majority needed to pass articles of impeachment if the rest of the caucus does not go along, but a significant increase since last week.

On Monday, The Washington Post and other media outlets reported that Trump instructed his chief of staff to place a hold on $400 million in military aid for Ukraine in the days before a late July phone call with Ukrainian President Volodymyr Zelensky.

Trump told reporters Tuesday that his request to withhold the aid was due to his desire to see greater European contributions to Ukraine’s defense, and not linked to whether the country would investigate the Biden family, which media outlets have reported Trump brought up on the call with Zelensky.

Senate Majority leader Mitch McConnell said Tuesday he was never given an explanation for why the funds were being withheld, despite pressing senior administration officials about it at the time.

The White House has publicly sought to link the latest controversy — over whether Trump sought help from a foreign country to go after one of his chief political rivals — to the Russia election meddling investigation, which they have asserted exonerated the president, though it listed numerous instances of possible obstruction of justice.

“The media pushed the Russia lie for almost three years with no evidence, and now they are doing it all over again,” White House spokesman Hogan Gidley told NBC News in a statement Monday. “These allegations are completely false, but because the media wants this story to be true so badly, they’ll once again manufacture a frenzy and drive ignorant, fake stories to attack this president.”

Trump's campaign has also argued that the latest effort is another attempt by the Democrats to overturn the 2016 election results.

"They’ve always wanted to impeach him, and they’ve just been shopping around for an excuse," said Trump campaign communications director Tim Murtaugh.

McConnell's reaction to the news late Tuesday echoed the White House's line of attack, accusing Democrats of “searching for ways to reverse their 2016 election defeat since before President Trump was even inaugurated and a "rush to judgment" and saying the move “simply confirms that House Democrats’ priority is not making life better for the American people but their nearly three-year-old fixation on impeachment.”

So did House Minority Leader Kevin McCarthy's. "I realize 2016 did not turn out the way Speaker Pelosi wanted it to happen," said McCarthy, R-Calif. "But she cannot change the laws of this Congress. She cannot unilaterally decide we’re in an impeachment inquiry." House Minority Whip Steve Scalise, like the president, called the impeachment push a "witch hunt" that was being "used to try to go and usurp the results of an election in 2016."

While sources close to the president said they didn’t want to see impeachment, they were prepared to argue it could be “helpful” in mobilizing the core supporters inside the president’s base.

Some allies predicted the move would backfire on Democrats, particularly if the transcript being released Wednesday failed to show a smoking gun — and the president’s campaign was already working to capitalize on the upcoming impeachment fight.

Over the course of several hours, the campaign sent multiple fundraising pitches to supporters, including the launch of an “Official Impeachment Defense Task Force." It also released a video attacking Democrats calling for impeachment, which Murtaugh said had been "ready for weeks in case the Democrats were that dumb. And they were.”

Inside the White House, this round of impeachment talks was viewed as more politically perilous than during the Russia investigation, said one White House aide. Whether and how the White House is able to spin the transcript — and what the polling indicates over the next few days — will determine if this is yet another scandal to weather or a marked shift in public sentiment, the aide said.

Ahead of the Pelosi announcement, Republicans in Congress had been largely silent on the issue, with allies backing his allegations of corruption by Biden. The most critical GOP reaction came from Sen. Mitt Romney, R-Utah, who told NBC News Monday that Trump “should make available the whistleblower complaint that has been deemed to be credible and urgent."

"I think it'd be very helpful to get the bottom of the facts," Romney said. "If they don't, it will be up to the House to decide how to proceed.”