Tedski scoops us on the Rasmussen poll showing that McCain is vulnerable in a GOP primary to J.D. Hayworth, the sportscaster-cum-congressman-cum-radio talk-show host.

An interesting tidbit that shows the growing split within the GOP:

Hayworth, a conservative former U.S. congressman who now is a popular radio talk show host in Phoenix, is reportedly interested in the race but has not formally declared for it. He captures 59% of the male GOP vote, while McCain wins 58% of female voters.

Younger GOP voters like Hayworth more than their elders. McCain has a solid lead among the relatively small number of moderate and liberal Republicans in the state while Hayworth picks up a plurality (48%) of conservatives.

If the ongoing purge within the GOP were to claim McCain—McCain!—and J.D. were to become the nominee, that puts Democrat Rodney's Glassman's hopes of claiming the Senate seat in a whole new light.

ETA: On the other hand, Rodney probably can't be too happy about this line from Rasmussen:

For McCain, the GOP Primary appears to be his biggest challenge since no major Democrats in the state have stepped forward yet to run against him.