Mr. Madison, suggested that the Judges might be appointed by the Executives with the concurrence of 1/3 at least of the 2d. branch. This would unite the advantage of responsibility in the Executive with the security afforded in the 2d. branch agst. any incautious or corrupt nomination by the Executive.
Today, under the filibuster, the idea is that a minority of Senators can defeat the President's nominee, but Madison's idea at one point was that it should take 2/3 of the Senators to reject the nomination.
UPDATE: Betsy Newmark takes this post as a prompt to read through the whole debate on the subject of judicial appointments (and to make her own observations). Really, I recommend reading through the original debates when these questions come up. It is very easy, at the Founders' Constitution website to click on individual clauses of the Constitution and get to the relevant historical materials. It's often quite striking how different these are from the things people are saying about them.