The PA Republican Party is in danger of becoming impotent, but I think that Santorum will defeat almost any challenger that the Dems bring up, unless 2006 is a really bad year for the GOP.
P.S. For those of you Democrats who think that Santorum is dead meat. You would do well to remember that he currently has the highest approval rating, in his state, of any U.S. Senator.
His approval rating is no higher than Rendell's. 2006 may be a washout for the GOP and Santorum and Coleman (MN) will be prime targets for the Democratic Senate Campaign Committee. Neither party should get cocky. I hate Santorum with a passion, but I know how big PA is and how different it is. However, the Southeast portion generally agrees with me and will turn out almost the same numebrs they did for Kerry in 2006. If that's the case, Santorum may have trouble. Remember, Bush is far less brash.