It's already been released.
Barr has told the committee that the report, unredacted except for grand jury information which is illegal to release, is available for congress critters to read and review at the DOJ. Last I read, only two congress people have taken Barr up on his offer.
So this is not about the unredacted Mueller report.
This is about discrediting Barr because the democRATS know what he's going to find when he starts looking into why the Russia/Trump investigation was started and who was involved in any illegal activity. And all of those people involved would be democRATS.
If they hold Barr in contempt, they still won't get the complete unredacted document because, one, it is illegal to do so, and two, Trump has invoked Executive Privilege to stop them.
This is all show on Nadler's part. Red meat for his radical Left base. Barr being held in contempt of Congress means nothing.
Just like it meant nothing to Eric Holder.
It meant nothing to Eric Holder because he had the Ministry of Propaganda at his back keeping it from being anything.
Along with the cooperation of Bush League Republicans.