Personally, my opinion is that a supporter of Rubio who may end up without a candidate would more likely go to Bush or Kasich instead of Cruz. To me, there is a world of difference between the two, and there is nothing good about Rubio in my opinion.
Rubio is more solidly pro-life than those two. He did have a great answer on that issue in the last debate, so those voters to whom that is a big issue may go Cruz. But I would agree that a lot of Rubio’s recently added support are from the RINO wing and would go to Bush/Kasich.