“In addition to refusing Congress’s demands for documents, Trump’s legal team is moving to prevent key witnesses from testifying at hearings, or to place strict limits on what they say, by looking to assert executive privilege retroactively over issues covered in the Mueller report. An appearance by by Robert Mueller himself, which had been rumored to be in the works for this week, didn’t take place. And it looks like Don McGahn, the former White House counsel, won’t be appearing next week, either. The Washington Post reported on Friday evening that “any hopes of . . . McGahn facing a congressional panel on Tuesday are slim, as the White House moves to block all current and former aides from cooperating with congressional inquiries.”

Source: The Trump Administration to Congress: Drop Dead | The New Yorker