Charles Grassley, the chairman of the Senate Judiciary Committee, and Mitch McConnell, the Senate majority leader, seem determined to call a vote next week on the confirmation of Judge Brett Kavanaugh to be an associate justice of the Supreme Court, even in the face of this week’s sexual assault allegations against him. Senate Republicans assume, correctly, that if they can hold the party line, his installation on the Supreme Court is a sure thing. This is certainly true — even if the Democratic caucus in the Senate holds firm against Mr. Kavanaugh, they simply lack the votes to block him....