U.S. House Intelligence Committee Chairman Adam Schiff said during an interview with MSNBC that the panel's impeachment report will be released to the public on Tuesday.

"We're putting the finishing touches on the (impeachment inquiry) report," Schiff said, according to MSNBC's transcript of the interview.

Earlier on Monday, U.S. President Donald Trump lashed out at Democrats, calling them a "disgrace" for holding impeachment proceedings while he attends a NATO summit in London and rejected participating in what he called "a hoax."

"The Democrats, the radical-left Democrats, the do-nothing Democrats, decided when I'm going to NATO ­­­– this was set up a year ago – that when I'm going to NATO, that was the exact time," Trump told reporters angrily on departing the White House.

"It's an absolute disgrace what they're doing to our country," he said. "The whole thing is a hoax. Everybody knows it."

Trump's comments come after Congressional Democrats Monday named four witnesses who will testify at Wednesday's public hearing in the impeachment inquiry of Trump held by the House Judiciary Committee in the Democratic-controlled House of Representatives.

The hearing, while academic in nature, will set the stage for the committee to begin determining whether Trump's alleged crimes in pressuring Ukraine to investigate a domestic political opponent meet the constitutional impeachment bar.

The panel will also receive a report on Tuesday from the House Intelligence Committee laying out the evidence Democrats say shows Trump abused his office for personal political gain. House Republicans issued their own rebuttal report on Monday, saying Democrats had not established an impeachable offense by Trump. 

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The 123-page defense of Trump was issued by the Republicans ahead of Democrats' impeachment report as a preemptive strike. The GOP document described Trump's hesitation to provide military aid to Ukraine "entirely prudent" and underlined how evidence presented at the hearings failed to shatter Republicans' united front.

Trump applauded the report on Twitter, calling for the involvement of the Supreme Court so as to stop Democrat's "impeachment hoax."

"Prior to landing I read the Republicans Report on the Impeachment Hoax. Great job! Radical Left has NO CASE. Read the Transcripts," Trump wrote on Twitter. "Shouldn't even be allowed. Can we go to Supreme Court to stop?"

Trump, who arrived in London late Monday for the two-day NATO Summit, accused the Democrats of trying to undercut him during his trip abroad for a NATO leaders' meeting playing out at a crucial moment for the 70-year-old military alliance.

Trump's trip comes amid ongoing quarrels over defense spending by NATO allies and widespread anxiety over the president's commitment to the alliance.

White House aides say the summit offers Trump an opportunity to counter the impeachment narrative in Washington and demonstrate to voters that he's keeping a business-as-usual approach while Democrats concentrate on the probe.

Trump's chief White House lawyer, Pat Cipollone, told the Democratic leader of the committee, Jerry Nadler, on Sunday that he was rejecting an invitation to send representatives to the session.

"We cannot fairly be expected to participate... while it remains unclear whether the Judiciary Committee will afford the President a fair process through additional hearings," Cipollone wrote.

Cipollone did not rule out White House participation in subsequent hearings. Throughout the drama, however, Trump has opted for stone-walling and flat-out resistance to what his supporters say amounts to a "coup."

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House Speaker Nancy Pelosi, in Madrid for a UN conference on climate change, declined to comment about the impeachment inquiry, saying, "When we travel abroad, we don't talk about the president in a negative way. We save that for home."

The hearing witnesses, announced by the committee on Monday, are Noah Feldman of Harvard Law School, Pamela Karlan of Stanford Law School, Michael Gerhardt of the University of North Carolina School of Law and Jonathan Turley of the George Washington University Law School.

(With input from Reuters, AFP)

(Cover: U.S. President Donald Trump (R) and first lady Melania arrive at Stansted Airport, ahead of the NATO summit, in Stansted, UK, December 2, 2019. /VCG Photo)