I think the GOP and Grassley in particularly were envisioning another Clarence Thomas situation. More important, Kavanaugh's handlers are definitely expecting that. Thomas rode out the accusations and is still sitting there as the most conservative vote on the Court.
Now, I'm hard pressed to imagine Kavanaugh getting away with accusing the panel of "a lynching", but with everyone in the country currently being fingered as a sexual predator, they reckoned on being able to sell this to the entire GOP Senate rather easily.
I hate to say it but Grassley was right. They should have rammed it through for a vote last week. They're afraid of November, though, so decided to give it the pretense of being fair and opened the door to several more accusations. If they rushed the vote, they'd be jeopardizing not just the House (already seriously in play) but also the Senate.
The winning move for the GOP will not be played, I think. Withdraw his name and make hay of it in all your political ads through the election. Play him up as a martyr to the cause and blame the feminazis. Submit someone else from the El Creepo Federalist Society recruiting list. I think the GOP aren't willing to do that.... yet.