another top state department official, and the former u.s. ambassador to ukraine, most recently recalled by president trump, kind of out of thin air, it appeared at first, and her firing, if you will, is in large part at the center of this entire ukraine affair. meantime, republicans are demanding that the whistle-blower and hunter biden be called to they have in these public hearings. but make though mistake, this week and the public hearings after this week will in large part determine the outcome of this impeachment inquiry. and by that i mean, does it convince the public, does it convince the politicians that are watching it play out? let's get to it. cnn congressional reporter lauren fox is on capitol hill. lauren, let's start with the democrats on this. what are you hearing about their approach, their strategy, all of the plans, how they're preparing for these hearings this week? >> reporter: well, kate, it's a blockbuster week on capitol hill and democrats are preparing in a big way. i've been told from a senior democratic aid that the preparations have been even more exhaustive than they were when robert mueller came tomm.