IMO, feeling enfranchised is more important than having a common language for campaigning, when it comes to feeling American.
If campaign ads in Spanish make immigrants feel more involved in the process, more power to campaign ads in Spanish.
Education and enfranchisement are two different issues for the purposes of this argument.
Schools should definitely emphasize English, as it helps with the construction of an American identity.
But, for Juan Pablo Montoya, who got here at age 36, Spanish campaign ads make sense.
Bottom line is we need to be more inclusive to build a common future, not exclusive.