I'm pretty sure there hasn't BEEN a vacancy in a presidential election year where there's a Senate that has a majority of a different party than the president.

The closest that came to that was Justice Kennedy, who was confirmed by a Democratic Senate in a Republican President's election year (Regan), but for a vacancy created the year prior.

I don't think you can call something a tradition when there hasn't been the opportunity for it to happen.

So you have to look all the way back to 1888 for a vacancy to happen in an election year with an opposing Senate, and in that case, the nominee was confirmed. It also happened in 1880 when a lame duck Hayes nominated Justice Woods who was confirmed He did have a nominee who wasn't voted on but was immediately re-nominated and confirmed by his successor.

So, McConnell is right in saying the last time a nominee from a presidential in an election year with an opposing Senate happened in 1888, but that was also the last time it actually happened until Garland's nomination.

This is also some slight of hand. McConnell was also referencing the so-called “Biden Rule” named after then-senator Joe Biden spoke on the Senate floor in 1992 indicating as the chairman of the Senate Judiciary Committee he would not vote on a nominee to SCOTUS until after the upcoming election that was about 5 months away at the time.

The catch here is that there was no vacancy on the Court. Biden was indicating what his position would be if a vacancy were to happen so its hard to point to it as evidence of consistency since the “Biden Rule” was never put to the test prior to McConnell citing it.