I think that Rubio is in over his head and starting to crack from the strain.
One of Saul Alinsky’s rules was that if there is someone who is making trouble and getting in the way of what you are trying to accomplish that you should give him a job, make him a part of the project so that whatever the outcome, he cannot complain. The Democrats did this to Rubio. He cannot back down now. It’s way too late. He fell for the Democrat flattery. I think that he was just too young and inexperienced to handle the job.
I heard him explain his interest in amnesty as advice from his mother, to not let down the other immigrants. I knew when I hear him blame his mother that he was done. No adult answers the question, “Why?”, with, “My Mother told me to do it.”
He's been an amnesty backer since his days in the statehouse. He did not fall for Democrat flattery. We fell for Rubio's deceit.