U.S. President Donald Trump speaks to reporters before leaving the White House in Washington D.C., the United States, on Dec. 2, 2019. U.S. President Donald Trump slammed an ongoing impeachment inquiry into him on Monday, as the next phase of the high-stake investigation was drawing near. (Photo by Ting Shen/Xinhua)

U.S. President Donald Trump slammed an ongoing impeachment inquiry into him on Monday, as the next phase of the high-stake investigation was drawing near.

Speaking to reporters outside the White House before leaving for a trip to London to attend a NATO summit, Trump called the impeachment inquiry "a hoax," while accusing Democrats of doing "an absolute disgrace" to the nation.

"So 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 said. "This is one of the most important journeys that we make as president."

The impeachment inquiry into the president, which House Speaker Nancy Pelosi initiated in late September, will enter a new phase this week as the House Judiciary Committee, chaired by Democrat Jerry Nadler, is slated to hold its first hearing on Wednesday on "constitutional grounds for presidential impeachment."

Legal scholars will provide testimony to the panel on that day as Democrats are considering whether the evidence turned up in their weeks-long impeachment inquiry warrants the drafting of articles of impeachment against Trump.

In a letter to Nadler on Sunday, White House counsel Pat Cipollone said they will not participate in Wednesday's hearing.

"We cannot fairly be expected to participate in a hearing while the witnesses are yet to be named and while it remains unclear whether the Judiciary Committee will afford the President a fair process through additional hearings," Cipollone wrote. "Accordingly, under the current circumstances, we do not intend to participate in your Wednesday hearing."

House Democrats are conducting an impeachment inquiry into whether Trump abused his office by pressuring Ukraine to launch investigations that could benefit him politically. Lawmakers are also examining whether the Republican tied a White House meeting or aid for Ukraine to those investigations.

U.S. President Donald Trump speaks to reporters before leaving the White House in Washington D.C., the United States, on Dec. 2, 2019. U.S. President Donald Trump slammed an ongoing impeachment inquiry into him on Monday, as the next phase of the high-stake investigation was drawing near. (Photo by Ting Shen/Xinhua)

 
Trump has denied any wrongdoing or a "quid pro quo." On Monday, he shared a link on Twitter of an interview that Ukrainian President Volodymyr Zelensky had with U.S. magazine Time so as to defend his narrative.

In that interview, Zelensky said he "never talked to the president from the position of a quid pro quo."

"That's not my thing," Zelensky continued. "If you're our strategic partner, then you can't go blocking anything for us. I think that's just about fairness. It's not about a quid pro quo. It just goes without saying."

The House Intelligence Committee concluded its public hearings prior to the Thanksgiving recess after it heard testimony from a series of current and former Trump administration officials and has spent the Thanksgiving recess drafting a report of its findings.

Lawmakers on the House Intelligence Committee are expected to begin reviewing a draft version of the report Monday evening and will vote at a business meeting Tuesday on whether to adopt the report, which would be sent to the House Judiciary Committee thereafter.

The White House has refused to cooperate with the investigation, accusing Democrats of an unfair process and a partisan attempt to nullify the results of the 2016 presidential election. Several senior administration officials have refused to testify, and multiple agencies have stonewalled Democratic requests for documents and communications.