I didn't hear that. What I have seen is that "Hispanic" residents consistently and continually vote predominately Democrat. Even this past election revealed that.
If they try to claim that the Mexicans helped out the GOP, I'd say that they're full of it and are using it to fluff up a reason as to why wide-open borders and amnesty are desired.
There's a few threads/posts around gloating over high Hispanic votes for GOP candidates. If I find one I'll flag you.