No. He got his ass kicked by too much in SEPA for it to matter. A liberal Democrat would have helped Santorum out west, but it would have not been enough to make up for the slaughter he took in SEPA. Santorum lost STPA by about 36 points, in comparison Bush lost SEPA by 26 points in 2004 and lost the state by 2.5 points.
Due to how bad Santorum got his ass handed to him in SEPA their is virtually no way a Feingold type of liberal would have lost to him. He would have improved on his numbers out west, no question about that, but it would not have been nearly enough to win due to the utter thumping he received in the SE
I agree with this assessment. A Feingold type liberal might have actually done slightly better than Casey in the Southeast. Santorum would not have made up for it elsewhere and I'm thinking even Feingold would have won PA by 8-10 in 2006. Sherrod Brown and Claire McCaskill won more conservative states.
Face it, PA is slightly liberal than the national average overall, but still enigmatic. We have pro-choice Republicans and pro-life Democrats in abundance.
Given the 2006 dynamics, there was no way Santorum could have won unless his opponent was Chaka Fattah. I think even Bob Brady would have beat him.