This whistleblower kerfuffle is getting interesting. How it's shaping up thus far...
On a phone call to a foreign leader, Trump makes a "promise" that alarms an intelligence official who had access to the call transcript (if not audio, we might wonder). The latter reports it to the IG, who deems the complaint credible and urgent, and then forwards it to the (acting) DNI, as prescribed by black letter law. The latter is then to inform the House Intelligence Committee within 7 days. But the acting DNI instead consults with the Justice Department, which agency is not permitted to be involved. Moreover, the White House may have been brought into the loop as well. A request by Adam Schiff for the complaint was ignored, and tomorrow (Thursday) the acting DNI is supposed to appear before the HIC.
The whistleblower laws are very clear, but the Barr JD could be glomming onto one clause which states something to the effect that the IG (? memory hazy here) is not subject to oversight by the Justice Dep't, which they might be using to twist to some new interpretation.
The foregoing is my flawed recollection after seeing this covered by Lawrence O'Donnell.
It sure looks like some number of Departments have been corrupted and are acting to shield a POTUS who is a clear security risk/threat.
One mooted motivation: Trump could have promised Putin normalized relations during the call in which aid to fight Russian wildfires was discussed, in return for help in the next election. A theory, to be sure, but well within the bounds of possibility. Trump will certainly be desperate to not lose in 2020, because of the statute of limitations having not run out on some of his shenanigans, particularly the campaign contribution business Cohen is currently doing time for.