A CNN story on Monday revealed that there was internal conversation within Marco Rubio's campaign that could lead to him dropping out — even before the Florida primary on Tuesday.
The story was quickly denied strongly by Rubio's campaign, but CNN so far has not backed away. The report was that Rubio had fallen so far that he was unlikely to win in Florida. Rather than losing Florida by a large margin, as he is currently behind Trump in the Florida polls, the idea was that Rubio would be stronger long term politically if he avoided suffering an embarrassing defeat in Florida.
Right now, Rubio is polling behind Trump in Florida, but the race appears to be tightening. Rubio maintains he has always been an underdog; that Florida is his state; and that he intends to win there. So the rumors that CNN is reporting on may be just that, rumors.
However, even if Rubio stays in through Florida, Florida is for him a "must-win" state. So his team is pouring their efforts into the contest that is now just a week away.