The flaw in GWB is that he has left a “base” that practically no longer exists and is totally demoralized. And he has procured no Democrat support to replace that base, as he apparently sought to do.
Have to give it some more thought, but it seems to me that the base of a political party can and sometimes does change over time. To me, it looks like more of “natural” process, not one influenced all that much one way or the other by a president.
Because, by definition, a base is a group of people who really have nowhere else to go politically.