“The President has directed Mr. Dearborn and Mr. Porter not to appear at the hearing scheduled for Tuesday, September 17, 2019,” Cipollone wrote to House Judiciary Committee Chairman Jerrold Nadler (D-N.Y.) on Monday evening, later adding: “The Department of Justice has advised me that Mr. Dearborn and Mr. Porter are absolutely immune from compelled congressional testimony with respect to matters related to their service as senior advisers to the President.”

The move was largely expected by House Democrats, who argue that the administration’s frequent immunity assertions over potential witnesses in their probes are bogus. They’re currently challenging many of those claims in court.

The White House did something similar to stop other top Trump officials Democrats sought to haul into the witness chair, including former White House counsel Donald McGahn, from testifying. An appeals court is expected to rule on the claim over McGahn’s testimony as soon as late October.

In a letter to the panel, Porter’s attorney said his client was in an impossible situation, a fight between two branches of government that must be resolved before he appears before lawmakers.

“Mr. Porter has served in all three branches of the Federal government and is mindful of their respective constitutional responsibilities and prerogatives,” Porter’s lawyer Brant W. Bishop wrote to the panel in a letter Monday night. “He now faces competing and incompatible demands from coordinate and coequal branches . . . Such conflicting demands must be resolved through an accommodation between the Executive and Legislative branches, or by the Judiciary.”

He added: “In the meantime, because the inquiry at issue relates to his service as a senior official at the White House, Mr. Porter must respect the White House’s instruction.”

Democrats’ Tuesday hearing, however, won’t be without fireworks. Far from it: Trump’s combative former campaign manager Corey Lewandowski intends to testify, pushing back on Democratic assertions that Trump did anything wrong.

The questioning, which many expect to be heated, will be the first time House Democrats will have a key witness in the Mueller investigation testifying in public — a move they welcome even if he’s fiercely loyal to Trump.

The White House, in a letter to the committee, told Nadler that Lewandowski is not allowed to answer any questions about his communications with the president beyond what was in the Mueller report.

“As explained below, Mr. Lewandowski’s conversations with the President and with senior advisers to the President are protected from disclosure by long-settled principles protecting Executive Branch confidentiality interests and, as a result, the White House has directed Mr. Lewandowski not to provide information about such communications beyond the information provided in the portions of the report that have already been disclosed to the Committee,” the letter reads.