Because Cruz knows many of his supporters are falling for this Trump catastrophe and is looking for Goodwill for the eventual (hopefully) day that Trump drops out and endorses Cruz.
A RINO-voter leaning towards a Bush, Rubio, Christie is not someone that would vote for Trump. Trump is taking away voters from primarily Cruz and Walker.
That makes no logical sense because many are claiming Trump is not conservative. So why would conservative voters switch from Cruz & Walker to Trump? If Trump is a liberal, as some claim, he should be peeling votes away from more liberal candidates like Bush & Christie.
You can’t have it both ways.
If any other republican is the nominee and Trump goes third party I will vote for Trump.
I will be okay with Trump as long as Cruz is okay with Trump.
Also, I have been reading Trumps' books and he is much more conservative than you will hear people on FR or the media say.