Anderson Cooper 360

White House To House Dems: Pres. Trump Won't Participate In Impeachment Inquiry, Claims It's Unconstitutional; White House To Democrats: Pres. Trump "Cannot Participate In Your Partisan And Unconstitutional Inquiry Under These Circumstances"; WH Accuses House Dems Of Illegitimate Impeachment Process; WH To Dems: Impeachment Inquiry Seeks To Reverse 2016 Election And Influence The 2020 Election; White House Official Describes Pres. Trump's Call With Ukrainian President As "Crazy And "Frightening"; Sources: Former GOP Congressman Trey Gowdy Joins Trump's Legal Team; Will Serve As Outside Counsel In Impeachment Fight; CNN: Pres. Trump Told Energy Secy. Perry And State Dept. Officials To Talk About Ukraine As Early As May; Sanders Campaign In Recovery Mode; Sources: At Least One NSC Official Alerted The WH's National Security Lawyers About Concerns Related To President Trump's Ukraine Call; Sources: Pres. Trump's Ukraine Call Deeply Troubled National Sec