There really wasn’t a lot of difference between them in terms of philosophy once Trump outlined his positions. I think in many ways, Cruz pulled him to the right just as Sanders pulled Hillary to the left. Trump was a force of nature, whereas Cruz was not. Maybe some day his time will come. Who knows.... but his support is needed as the Senate margin is thin (for two years).
Actually Trump pulled Cruz to the right. There was no talk of unchecked illegal immigration costing us our sovereignty/country (from Cruz) until Trump entered the race. Trump was also to the right of Cruz when it came to Hillary/Soros thugs shutting down the First Amendment.