After Paul, say good bye to Rubio.
I think Rubio hangs in for a while.
As candidates leave the race their support has to go somewhere. Even negligible support (like for Perry, Walker and Paul) starts to add up. It becomes more of an endurance test than anything else.
Rubio also has nowhere else to go, since he’s foregoing reelection to the Senate for this Presidential run. Having nothing to lose creates a completely different set of motivations for a candidate when it comes to the leave or stay in decision.