You're kidding, right? I'm starting to think the whole network is run by the Democrats, as spelled out on the NoAgendaShow. Bush and Rubio are the only guys those jerks ever promote. They're firmly establishment, and spend as much time bashing Trump and Cruz as they do Bernie Sanders.
Fox did a great job radicalizing the base, until they elected guys who couldn't be as easily controlled. Trump isn't beholden to them, so they're not fond of him. Carson never had much going on. Cruz is hated by just about everyone, for many good reasons. Rand Paul is too Libertarian for a corporate power like Fox to be too wild about. That leaves Bush and Rubio, maybe Christie, who they'll support as long as they don't make the same mistakes against conservatism that GWB did.