In FL, he would be directly targeting Cuban voters, most of whom immigrated legally, as they are refugees from Communist Cuba. As such, Rubio might even lose support among his own people, since it would NOT be in their interest to accept illegal immigrants, despite sharing a common language...
I mean, Ted's already released an ad in Spanish (the announcer is the same guy who narrates political ads for other candidates in TX).
I've seen the ad, and have a translation of it on a different thread: http://www.freerepublic.com/focus/news/3271004/posts?page=12#12
Make what you will of this, but I don't see how language would be an issue here. With that being said, however, English ought to be the official language of the US, and communication ought to be conducted in English.