Defining Republican Down

Larison is befuddled by the Crist/Rubio spin:

I don’t begrudge Crist’s conservative opponents their desire to compel him to take positions that are even more in agreement with their views. That is their prerogative, and it may even do some good on one or two issues, but it is curious how Crist’s successful political tactics are being held against him at a time when Republicans are no longer governing very many large states and when the party has declined nationally as well.

This is the same governor who campaigned actively for an amendment that reduced property taxes, so why would he be a top target of the Club for Growth? On policy, Crist is hard to distinguish from the tradition of former Gov. Jeb Bush, who angered a lot of conservatives with his liberalizing views on immigration but who has otherwise been widely respected and admired by many rank-and-file conservatives. Obviously, I am far removed from both Bush and Crist, so this does not recommend Crist to me, but what makes Crist the unacceptable “moderate” in the minds of movement activists that does not similarly tar Jeb Bush?