The hammer. The best part about Grassley's request is that the credibility of Feinstein/the Dems/ and their fake accusers will be exposed.  I have the impression that Grassley and others are super serious about getting to the bottom of things, exposing and if need be prosecuting those involved in the Kavanaugh hit job scheme because they feel they have an obligation to protect and redeem Kavanaugh's reputation as a political(he needs to be seen as a man of character and an impartial judge) and personal matter(i.e. he's a fucking good man, one of the best as the Washington Swamp goes and this is a profound injustice).  They best way to do all that is with teeth.