To fire Mueller- the law is clear- He needs Rosenstein to carry out the execution of the Mueller investigation- He must order Rosenstein to fire Mueller. Rosenstein IMHO, would refuse. Then Trump has 2 choices- buckle under or fire Rosenstein.
Brandt was next in line after Rosenstein, she submitted her resignation & left effective 20 Feb 18. Trump retains the right to appoint her replacement
If he fired Rosenstein, next in line is temp appointed (Brandt's replacement??? Congress needs to approve her replacement, unless it is an appointment made when Congress is in recess) - now would they fire Mueller or themselves be fired? If they refuse, next in line, rinse and repeat.
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The investigation would still continue under the FBI.
The political repercussions would be immense.
Here is a link to the lineup of replacements and the order they fall into
https://shugerblog.com/2018/02/09/a...who-is-next-in-line-on-mueller-investigation/
Recess appointment
https://en.wikipedia.org/wiki/Recess_appointment
https://www.senate.gov/CRSpubs/3d313cc2-9515-4533-b1f0-3f762cd09007.pdf