In one word, polling. If it’s as bad as I think it might be (and tonight isn’t going to help), he might do it in order to save face, and run for Governor in ‘18.
Rubio has already complained that he doesn’t like his Senate job, and has now bombed as a presidential candidate (despite being the anointed GOPe candidate). Can a FL governor succeed himself? Or is Scott planning to retire?
No matter what he does, Rubio will have to do some total redefining of himself and his image. The Rubio who ran here has done poorly, and with good reason.