Ah yes, the old "GOP establishment". Personally, I have no idea what that is, who they are, and where they can be found.
Whomever that may (or may not)be, what they aren't is the "Party".
You actually believe that?!? LOL!!
You're right. That's EXACTLY why Mitt Romney won the nomination in 2008 - oh, wait.
We haven't had a brokered convention in a generation, or longer. If you can convince enough Republicans, and in some states independents too, that you're the man for the job, you'll win. If you can't, you won't. Old men huddled in back rooms smoking cigars has nothing to do with it, although those guys make for great fall men when incompetent candidates fall flat on their faces.