There are only 4 cases in American history of a Senate taking no action on a Supreme Court nominee. Before Merrick Garland the most recent was 1853.
That was William C. Micou, nominated by outgoing President Millard Fillmore after Franklin Pierce had already been elected.
Prior to that, for the same seat, Fillmore nominated Edward A. Bradford in July. By the time of this nomination Fillmore had already failed to secure the Whig nomination for President that year in favor of General Winfield Scott.
This was also the closest to an election that any President ever nominated a Justice, until Amy Barrett in September of this year.
The remaining example of no action was in 1845 when John M. Read was nominated by President John Tyler. As with Micou and Fillmore, the election had already been held and James Polk had been elected.
Also worth noting that Tyler and Fillmore were both unelected and had assumed office upon the deaths of William Harrison and Zachary Taylor. They were among the weakest of Presidents, both failing to receive the nomination of their own parties.
Merrick Garland of course was nominated nine months before an election with eleven months to go in the term of a twice elected President.
Mitch McConnell's "precedent" is nothing more than a tissue of half truths and outright lies. It even whitewashes the far more recent confirmation of Anthony Kennedy in 1988.
Now to be clear...there have been rejections, postponements, nominations withdrawn when it was clear they would fail, if you go back far enough some nominees declined. And one even died.
But simply ignored by the Senate? That's it. Four times. None remotely comparable to Merrick Garland and none in over 160 years.