Nobody stays on message better than Ted Cruz.
So far, Cruz is the class of the field.
I have also said for a while that Cruz's biggest asset and biggest liability is his self chosen position as the Republican's top fire eater. Cruz will have people coming out of the woodwork to vote for him. Cruz has made a lot of enemies as those without a moral compass are at best disdainful (more often implacable enemies) of those who point out their lack of morals.