It has appeared to me, over the last couple election cycles, Republicans are trying to construct a base from the middle. They disavow, and openly criticize their own base, and of course criticize the extreme left. I don’t know if this is even possible, but look at the way Republicans use the term tea party to scare voters. I think they think if they can successfully marginalize the base of both parties, they will be the recipients of support from everyone who claims to be moderate. I think Bush is either an increment, or is trying to test the hypothesis.
I am probably missing a lot of facts that blow my thinking out of the water, but this has been in the back of my mind for a while.