Grassley knows more than he is letting on. This is apparent in a new letter sent to Adam Waldmann (a lawyer, naturally) of Endeavour Group.

In this letter, Chuck seems to call out Steele and his relationship with the Russian Oligarch Deripaska. It seems that Grassley is implying that Steele was actually working for the Russians when he compiled his unsubstantiated and phony dossier. It seems the Russians played Steele like a fiddle, while he was getting paid by the DNC. He was so eager to believe the bullshit he threw out all common sense and reported exactly what they told him without verifying anything (Trump Derangement Syndrome is real!) Considering how his phony dossier was the impetus for the FISA warrant (and abuse) it would seem that Chuck is really onto something here and knows the whole story but wants to get people on record.

If you read between the lines, it would seem that Chuck got wise to some knowledge and wants to get this all on record when the hammer falls.