Who will Trump go after most in debates?

[Likely Voter]

Donald Trump may be a joke candidate but he could do some damage in the debates. He is no wilting flower and he is best when he is on the attack.  So who will take the brunt of the attacks in the debates? Who is going to get fired by Trump?

[Likely Voter]

In his campaign so far Trump has gone after Bush the most. While this is certainly mainly due to him being a 'frontrunner' I also think there is some personal beef too. He also has been taking a good number of shots at one of the other frontrunners,  Rubio, but not Walker. I think that is because Walker has shown him a level of respect, apparently visiting him and giving him a present recently.

And with Regards to Rubio, I suspect that Bush and Walker and others are happy that Trump is now in the ring. Not only is Rubio now polling at the top of the average, he has the highest favorability ratings and very low negative ratings. He is essentially an empty vessel that people put their own hopes into (ala Obama). For Bush or Walker to go after Rubio it would probably backfire, so they must be happy that finally someone is taking Marco out for a spin.