david mueller. how realistic is that and where could that end up? it is a gamble for both the white house and for robert mueller. >> i think less of a gamble for mueller than president trump about whether he sits down or not. bob mueller is clearly going to call the president to voluntarily testify. come in with his lawyers, sit down around the table and go through things. and that way vulnerability for the president, if he forgets or something or misstates something. but if he does not, then the likelihood is very high that mueller will do what he would do in a standard case and that is issue a subpoena and put the president in front of a grand jury. the danger for the president there is he will not have his lawyers by his side to talk to him about the answers before he gives them. he is sort out of there on his own, he's a trapeze artist without a net. >> and how much could his comments come back to hurt him where he has said publicly, you know, i look forward to sitting down with robert mueller, he said repeatedly i have nothing