Any incumbent who earns less 50% support is considered potentially vulnerable and McCain has been hovering around that mark all year. The 2008 Republican Presidential nominee cannot be comforted by the fact that his level of support in early primary polling is similar to the numbers for Arlen Specter. Specter, defeated by Joe Sestak, led in just about all early polling but could never get much above the 50% level of support. That provided Joe Sestak with a chance to defeat the 30-year veteran of the Senate yesterday.

One indication of McCain’s growing concern about the primary race is his recent shake-up of his campaign staff, replacing his top local staffers with major national political advisers. Still, there is a difference between having an opportunity and capitalizing on it. It remains to be seen whether Hayworth can find a message that will put him over the top in August.