Four White House officials summoned by House Democrat impeachment investigators will not testify behind closed doors Monday, defying subpoenas to appear.

John Eisenberg, the National Security Council’s lawyer; his deputy, Michael Ellis; Robert Blair, a senior adviser to Acting Chief of Staff Mick Mulvaney; and Brian McCormack, the associate director for natural resources at the Office of Management and Budget, are all refusing to participate in their scheduled deposition Monday.

House Democrats pursuing the partisan impeachment inquiry reportedly subpoenaed all four to testify in private.

In a letter sent to White House Counsel Pat Cipollone on Sunday, the U.S. Department of Justice’s (DOJ) Office of Legal Counsel concluded that high-level presidential advisers like Eisenberg have “absolute immunity” from congressional subpoenas for testimony, CBS News reported.

Assistant Attorney General Steven Engel argued that White House attorney Eisenberg is under no obligation to comply with the subpoena issued by House Democrats conducting the impeachment probe.

“You have asked whether the Committee may compel Mr. Eisenberg to testify,” Engel wrote in the November 3 letter.” We conclude that he is absolutely immune from compelled congressional testimony in his capacity as a senior adviser to the President.”

Cipollone then informed William Burck, Eisenberg’s lawyer, that President Donald Trump “directs” the White House attorney “not to appear at the Committees deposition” Monday.

CNN noted:

As more witnesses in the impeachment probe continue to refuse to give testimony, House investigators are signaling they are prepared to begin the next phase of their inquiry — even if their subpoenas are ignored across the board. A number of House Democrats told CNN that it’s time for that next step, saying they’ve already built enough evidence to advance the proceedings to the public stage.

House Democrats pursuing the impeachment inquiry are supposed to be trying to determine if Trump abused his power by allegedly pressuring Ukraine to investigate corruption allegations against White House hopeful Joe Biden and his son, Hunter, in exchange for aid.

There are signs, however, that the partisan probe may go far beyond Ukraine. Trump and Ukraine have denied the allegation at the center of the impeachment probe — that the president leveraged aid to pressure the Eastern European country to investigate the Bidens.