been preparing for this hearing for some time. he knows his credibility will be challenged, so he's bringing documents with him. he's going to tell some sordid and potentially, in the words of lanny davis, his spokesperson, chilling stories about how donald trump has behaved. the russia material is off limits at the open hearing, but he can discuss the hush money payments to women, alleged corruption at the trump foundation, the way donald trump has avoided taxes, and otherish shoo you issues with his family business. the michael cohen we reported about last week is he's cooperating with investigators in manhattan. he's giving information about the trump foundation and inaugural committee. he'll have a lot to say. he may not be able to say what he is telling the prosecutors. >> for folks not following this as closely as you have, cohen won't be able to testify about the russia stuff in the public hearing for what reason? >> well, that's a great question