Interesting Salon article on this subject.
McConnell's filibuster threats are already backfiring: Biden signals support for major Senate reform | Salon.com
Sen. Mitch McConnell, R-Ky., had been making a mockery of Senate norms for years as Majority Leader and he had made it quite clear those old-fashioned notions were no longer operative. There was a time when elected officials would express their support for a new president of the opposite party, wishing them success for the good of the country. McConnell broke that norm during Barack Obama's first term when he openly admitted that he considered it
his top priority to deny Obama a second term. He didn't believe it was in his interest to accommodate or negotiate in good faith and instead began a campaign of total obstruction so that the president and his administration would fail and the Republicans would take back the White House.
While this sort of scorched-earth tactic wasn't unprecedented, it was unusual for a national political leader to flaunt his intentions so boldly. There used to be a penalty for being so openly ungracious but McConnell found that it didn't hurt him so he kept right on going, purposefully paralyzing the Obama administration, making it obvious that democratic norms were no longer functional. And left unable to confirm any members of the judiciary under McConnell's obstructive tactics, the Democrats had to eliminate the filibuster norm for everything but nominees to the Supreme Court. After he won the majority, McConnell brazenly blocked the nomination of Merrick Garland, Obama's choice for the high court, for months only to scrap the filibuster for the Supreme Court as well once Donald Trump won the White House and nominated a Republican to the seat. McConnell's excuse, which he made up out of whole cloth, was that in an election year the seat should stay empty because it should be up to the people to decide which president should choose the new justice.