From a new book

McConnell knew many of his rank-and-file were torn over how to handle the situation — and that in their uncertainty, they would look to him for guidance. If he declared the trial to be constitutional, breaking with Trump in the process, he could set the stage for a party mutiny, helping the GOP turn the page on Trump for good. It was an appealing prospect: conviction could enable the Senate to bar Trump from holding office again — and McConnell didn’t ever want Trump in office again.”

“But in all his years as GOP leader, McConnell had never led such a rebellion. And that day, he wasn’t sure he was up to the task.”

Shorter: cowardice