“Does any party survive attacking it’s own base?”
Let’s see, the SCF wants to get rid of Senate minority leader and you expect the minority leader to embrace the SCF.
Sorry, it does not work that way.
The Senate Minority leader acts like a member of the majority party. SCF has very good reason to want to “get rid” of him. They didn’t willy nilly just decide to endorse his opponent one day for no reason.