A Washington federal trial judge on Thursday set a speedy timeline for addressing questions over whether the Trump White House can lawfully block current and former top officials from speaking to House investigators leading the impeachment inquiry.

U.S. District Judge Richard Leon of the District of Columbia was asked last week to assess a clash between Trump and congressional Democrats, an interbranch tug-of-war that flared up over a House subpoena seeking testimony from former national security adviser Charles Kupperman.