The DOJ isn't doing anything "behind the scenes" right now. They are part of the Deep State.
Read the Holder tweets. Holder is criticizing Nunes, Jordon, Meadows and a few others in Congress who are pressing the issue.
Holder is afraid of a contempt vote, that Trump will then fire Rosenstein, that the DOJ will then be cleaned out and that the Insurance Policy will be gone.
Only then will the prosecutions start.
Holder knows that this FISA abuse patterns and spying on political adversaries leads right back to him.
IMHO this went full scale after Obama got butt sore over the Citizen United ruling. He turned the spooks, NSA, FBI intelligence and the IRS lose on Republicans AND most likely Justices on the USSC.