we wouldn’t be here if the GOP had shut down Mueller the minute it was known Clinton/DNC funded/created(?) the fake Russian dossier... and set up an investigation of the spy-gaters and coup-plotters.
The never Trumpers in the GOP were secretly with the Dems.
In case you are not aware, Congress is the legislative branch and Mueller was part of the executive branch. Trump could have stopped it, but it definitely would have led to impeachment, so he just played it out because he had no choice.
So in case you missed the first sentence, the only person who had authority to shut down Mueller, that person was Trump.