Lauren Elizabeth, Joe Manchin is what he is: -- an anomaly. He is a Democrat within a very Republican state. If the Democrats didn't have Manchin, they would NOT have a Senator from West Virginia or the Senate. Take it for what it is.
He will not be a threat to the presidency because he has zero sex appeal. That said, if the left of the Democratic Party succeeds in getting their perfect nominee, they will almost certainly lose. They had a master, Bernie Sanders, who lost. Twice.
Hopefully, Joe Biden will conclude that he is too old and open the way for youth and talent that the Democratic Party has plenty.
The obvious excellent choice would be Secretary Buttigieg, but there are others.
Many thanks.