It's happening in Arizona. Perhaps it's already happened. PPP's new poll:

There has been a great deal of movement along racial lines. In the September poll Goddard had a 3 point lead with white voters, but he now trails Brewer by 8. At the same time he's increased his lead with Hispanic voters from 20 points to 46.

PPP also finds that, if J.D. Hayworth wins the GOP nomination, he'll trail almost completely unknown Democrat Rodney Glassman 42-39. Of course, McCain, too, is highly unpopular in Arizona, but strongly leads Glassman, albeit pulling in just 49% on the process.