How do we know he's not going to turn it down again?
The first time wasn't a "formal" nomination IIRC, I think Trump simply stated that he "intended to nominate" Marino to the post. Sounds like Trump really wants him, though in the past he said that he had family concerns, and then some people also suspected that he has some skeletons in his closet and doesn't want to have confirmation hearing publicize some of them. Someone (on RRH, I believe) said that this post actually doesn't require Senate confirmation, but I have been told otherwise.
