He's a young guy who had a bad week in a national campaign. The potential candidates for statewide office in Florida aren't necessarily going to be on the level of the opposition here.
The thing is, there are already two statewide officeholders who have been preparing for this race for years. From what I've been hearing, Adam Putnam has already nailed down commitments from the establishment while Jeff Atwater has been getting a lot of the Tea Party people revved up to support him. Where is Rubio, who never had much moneyed Florida support ANYWAY, supposed to get his resources and organization from? His support came from being a not-Crist Republican, not his own popularity; now that the party has left him behind what will he have left?