Mueller Report Vicious Circle
The Mueller Report "did not establish" that members of the Trump Campaign conspired or coordinated with the Russian government". Which means they can not prove it happened with full confidence in that conclusion.
They can not prove it happened with full confidence because Trump Obstructed Justice with his witness tampering, using among other things the non subtle dangling of pardons to witnesses who could have helped establish conspiracy and/or coordination with the Russian government: Think Stone and Manaford for starters.
Because "collusion" was thus not clearly established, Barr notes that the Special Counsel did not establish that the President was guilty of an underlying crime. He then notes that the lack of such evidence bears upon the matter of "corrupt intent" on the part of the President, making Obstruction harder to establish, since "corrupt intent" is a key element in proving Obstruction of Justice beyond a reasonable doubt.
Therefore the success of Trump's Obstruction of Justice prevented an underlying crime from being established, and the fact that no underlying crime was established prevents Obstruction of Justice from being proved beyond a reasonable doubt.
At least that's how Barr gets to where he wants to be.
= new reply since forum marked as read
But I went with yours. I hate being a mediocre speller with mediocre eyesight that usually is good enough at a keyboard except when I get tempted to take the first option that spellcheck gives me 
