Mr. Madison speaks

on the Judiciary:

Mr. Madison observed that he was not anxious that 2/3 should be necessary to disagree to a nomination. He had given this form to his motion chiefly to vary it the more clearly from one which had just been rejected. He was content to obviate the objection last made, and accordingly so varied the motion as to let a majority reject.

from this marvelous site that contains records from the debates at the constitutional convention in 1787. HT Ann Althouse