The White House said Sunday it will not participate in a new hearing in the House Judiciary Committee this week.

The Judiciary Committee’s first hearing on the impeachment of President Donald Trump over his dealings with Ukraine is scheduled for Wednesday.

In a letter to Judiciary Chairman Jerry Nadler, White House counsel Pat Cipollone said the witnesses are still to be named and it remains unclear whether the Committee will provide Trump with a fair process through further hearings.

Read more: White House to not attend Judiciary Committee hearing