lawmakers. three hours from now, a key witness in the are president's impeachment inquiry. is scheduled to testify. charles kupperman who listened in on that july ukraine phone call is asking a federal judge to decide whether he must testify before house investigators. suzanne malveaux is live for us on capitol hill with more. so he doesn't want to, but a judge may decide he has to today? >> reporter: that's absolutely right. we'll find out shortly. this impeachment inquiry covered through the weekend, i covered a rare saturday session, real doubt this morning whether charles kupperman is going to show. because as you mentioned he's now putting this in the hands of a federal judge to decide whether or not he'll be compelled to testify today. house democrats threatening to hold former deputy national security adviser charles kupperman in contempt of congress if he doesn't obey a