This is the 'tell' in this article.
Trump thinks he can threaten a man of Mueller's reputation is pathetic. Trump is in a new league, one that will consume him.
That may have been by design, according to a person who spoke to Mr. Trump on Tuesday. The president was pleased by the ambiguity of his position on Mr. Mueller, and thinks the possibility of being fired will focus the veteran prosecutor on delivering what the president desires most: a blanket public exoneration.
Trump Stews, Staff Steps In, and Mueller Is Safe for Now
By GLENN THRUSH, MAGGIE HABERMAN and JULIE HIRSCHFELD DAVISJUNE 13, 2017
http://www.nytimes.com/2017/06/13/us/politics/robert-mueller-special-counsel-trump.html?hp&action=click&pgtype=Homepage&clickSource=story-heading&module=first-column-region®ion=top-news&WT.nav=top-news&_r=0

DO SOMETHING!