That's a silly question.
You should know better than to ask a question to which you don't already know the answer.
I'll pick two easy pieces of evidence.
First, he is carefully, and wisely, not only NOT attacking Trump, he is supporting him. That's what the back-up, second place, kind of people do.
Second, Trump is the guy who bullied the illegal problem to the center stage. Cruz and Trump both have similar positions, but Cruz struggled for 3 years, and failed to do what trump did in less than 3 weeks.