Federal Judicial Nominations

Year-end analysis by Russell Wheeler of Brookings:  "Judiciary Committee chair Patrick Leahy rigorously honors a committee tradition of not processing nominees who are opposed by either home-state senator [blue slip].  It is thus pointless for the administration to send the Senate a nominee without those senators’ assurances they will not block the nomination." 

Perhaps unsurprisingly and showing the separation of powers with today's divided government: "Of the 29 nominee-less vacancies, 26 were in states with a Republican senator."  

And the pattern back when party control was reversed: "At this point in the Bush administration, nominee-less vacancies were concentrated in states with Democratic senators."

I think the Framers are probably looking down at this and smiling with the sense that it's generally better to have some unfilled judgeships than allow one side of a closely-divided nation to quickly pull the judiciary sharply Left or Right.