There are some Cruz supporters, or Trump haters, who would never vote for Trump if Cruz got down on his knees and kissed Trump’s shoes. So, I don’t believe an endorsement would have helped him one bit. And I’m sure Trump had polls done showing that. So, he let him hang himself and at the same time made Trump look like the better man.
An endorsement would have made the people who do come over more enthusiastic. You could tell Trump was disappointed in Ted Cruz last night by the look on his face. He was out there to shake Cruz’s hand if he decided to endorse him.