Purportedly, because he blames McConnell for the passage of the infrastructure bill and the impending passage of (some form of) BBB.
But it probably has more to do with this:
Pubs, how long is it gonna take you to ditch this dead-weight asshole?! Until you do, your party is gonna be an unending circular-firing-squad shitshow!
But it probably has more to do with this:
Even though McConnell twice voted against convicting Trump during his two impeachment trials, he has nonetheless drawn the former president's fury by directly blaming him for the January 6th riots at the United States Capitol building.
Pubs, how long is it gonna take you to ditch this dead-weight asshole?! Until you do, your party is gonna be an unending circular-firing-squad shitshow!