The struggle between Democrats in the House and President Donald Trump over the Russia investigation intensified on Monday with the White House telling former Counsel Don McGahn not to honor a subpoena for his testimony on Tuesday before the House Judiciary Committee, as Democrats said it was all part of a broad effort the President and the Trump Administration to stonewall Congress about the Mueller Report and other investigations. In a letter to Democrats, McGahn's lawyer William Burck said, 'the President has unambiguously directed my client not to comply with the Committee’s subpoena for testimony.' 'Under these circumstances, and also conscious of the duties he, as an attorney, owes to his former client, Mr. McGahn must decline to appear at the hearing,' the letter added. Democrats said they would still convene the hearing at 10 am EDT on Tuesday, as they held out the possibility of finding McGahn in contempt, just as the same committee voted to find Attorney General William Barr in contempt for refusing to honor a subpoena for an unredacted version of the Mueller Report. Democrats wanted testimony from McGahn because of the information he gave to investigators for the Mueller investigation, in which McGahn detailed repeated demands by President Trump to oust the Special Counsel. While President Trump has sternly denied that he ever ordered McGahn to get rid of Mueller, the evidence offered by the Special Counsel painted a different picture. McGahn testified that the President called him on June 17, 2017 - about a month after Mueller had been named as Special Counsel - and pressed for Mueller to be ousted, an order that McGahn repeatedly ignored. On page 300 of the Mueller Report, 'McGahn recalled the President telling him 'Mueller has to go' and 'Call me back when you do it.'' The Mueller Report described McGahn - who reportedly answered questions for 30 hours over multiple interviews - as a 'credible witness with no motive to lie or exaggerate.' McGahn also claimed in his testimony that once news of the President's request was reported in the press, Mr. Trump then pressed McGahn to dispute the veracity of the story that the President had pressed for Mueller's ouster. McGahn refused to do what the President had asked. The White House based its refusal for McGahn to testify on a new 15 page legal opinion from the Justice Department, which said McGahn - as a former top adviser - was under no requirement to testify before Congress. 'The President's immediate advisers are an extension of the President and are likewise entitled to absolute immunity from compelled congressional testimony,' the Office of Legal Counsel opinion stated. In summary, the Justice Department said simply, 'we conclude that Mr. McGahn is not legally required to appear before the Committee.' Democrats denounced the decision, and charged it was just adding more evidence to what they say is a cover up, focused on obscuring obstruction of justice by President Trump. 'This move is just the latest act of obstruction from the White House that includes its blanket refusal to cooperate with this Committee,' said Rep. Jerry Nadler (D-NY), the Chairman of the House Judiciary Committee. 'The President is intimidating witnesses and stonewalling the American people and the rule of law. Congress and the American people deserve answers from Mr. McGahn,' said Rep. Mary Gay Scanlon (D-PA). '(T)he White House Counsel serves interests of the American people, not the President, and their conversations do not have the protection of blanket attorney-client privilege,' said Rep. Don Beyer (D-VA). 'It’s pretty clear what the Trump Administration is doing here,' said Sen. Chris Coons (D-DE), 'they’re trying to hide the facts from the American people.' Democrats have promised to move forward to hold McGahn in Contempt of Congress - but there has also been discussion of other penalties, from what is known as 'inherent contempt' - which could involve levying fines against those who refuse to cooperate with investigations by Congress. 'The cover-up continues,' said Rep. Adam Schiff (D-CA). 'And we will fight it.