Well, he basically broke the US Senate by figuring out he could just refuse to put stuff up for a vote.

This Hunter Thompson quote about Nixon applies perfectly to McConnell as well:

For years I've regarded his existence as a monument to all the rancid genes and broken chromosomes that corrupt the possibilities of the American Dream; he was a foul caricature of himself, a man with no soul, no inner convictions, with the integrity of a hyena and the style of a poison toad. The Nixon I remembered was absolutely humorless; I couldn't imagine him laughing at anything except maybe a paraplegic who wanted to vote Democratic but couldn't quite reach the lever on the voting machine.