It's going to be a bloodbath. And no matter who they end up with, there isn't a single one of them capable of beating Hillary.
But don't rule out Rand Paul doing something similar to Obama in 2008 and pulling the nomination from the caucuses and primaries with an unexpected "youth vote." Rand Paul's young people will be poor souls who think that, as a libertarian, he will give them legal marijuana.
And don't rule out Scott Walker, portraying himself as the only possible bridge between the tea partiers and the corporate-establishment Republicans. There are forces within the GOP already grooming him to be that guy. The question is: Can he pull that off?