I mean, I hate to bring this up, but George W. Bush is not likely to help anyone running, anywhere, anytime. His presidency is largely considered a failure. He didn't speak up when the Democrats turned him into the incarnation of Lucifer in his second term, taking his own party down with him. Why is he going to speak up now when no one is really interested in what he has to say any more? Bill Clinton, by the way, isn't going to help anyone either. And in the future, Obama is not going to be helpful to anyone either. We will have had 28 consecutive years of mediocre-at-best presidents. There isn't a living ex-president that could help anyone.
I voted for the man twice, so I hate to point out what is pretty obvious - he's a net negative to any Republican (but especially one with his last name).