Rubio is running such an awesomely smart campaign. Quietly building support while staying out of the spotlight for the most part. Staying above the fray by not insulting opponents or wading into controversial issues just yet. Speaking out strongly on foreign policy issues, his strength. Performing impressively in debates.
It's all by design, this long game. A quiet, strong presence in a slow, steady rise. Weariness with Trump's antics will set in, the truth of the incompetence of the outsiders on top will come to light, and all the other candidates will continue faltering.
There, in the middle of it, will be Rubio, the bridge, the hope, the only answer, peaking at just the right time. Not "Aha!" but "Duh!" - he's been there all along.
This could be a perfect description of the Rubio long-game.