Inside Mitch McConnell’s Season of Losses

When Mitch McConnell stepped out of his Senate office in the Capitol at 12:30 on Wednesday to announce that he would conclude his tenure as the longest-serving Senate leader in American history at the end of this Congress, I asked him why now.

McConnell grinned, said, “I’m going to cover that,” and then walked into the Senate chamber he’s wanted to serve in since being an intern here 60 summers ago.

His decision was no surprise. Having just turned 82 and facing health challenges since suffering a fall last year,...