You're kidding right?? Trump went after Bush and quickly relegated him to obscurity in the polls. Trump wants to win and he sees that Cruz is a threat. What should he do? Let Cruz win? Cruz has no qualms about going after Trump now that he saw he had a chance to win Iowa as well.
If you think calling Jeb low energy is going after someone and calling them a liar who is worse than Hillary Clinton I don’t know what to tell you. He treated Jeb like a joke. He has now treated Cruz like he’s someone to hate. And surprise, surprise- hard core Trump supporters are starting to hate him.