Manchin speaks of "the Democrats". He's extra-partisan. His posture is of one apart, who Stands Above It All. The Mountaineer has quite the elevated perception of himself. Even a senator from Deliverance has the same one-of-a-hundred vote as a senator from New York or California or Texas. Manchin has more clout because of his Above It All posture. Imagine a senator from Deliverance condescending to listen to the entreaties of the ninety-nine other supplicants come to bend at the knee and ask his favor. 

Very well, he quacks like a duck, he walks like a duck, he has the brains of a duck, kick him out of the Democratic caucus. Deprive him of committee chairs, put him on the committee for intellectual property instead of the mining or agricultural or incest committees. Be done with him.