Santorum gets his support from the more conservative, pro-life parts of the Republicans.
When he not only refused to help Toomey but actively campaigned for Arlen Specter, he partially lost that base of support. Also his ads sucked.
So Conservatives are THAT FREAKIN FICKLE? Boo freakin hoo..they didn't like his ads? THAT'S YOUR EXCUSE? Ridiculous. Maybe we just have to face the fact that we're not a Conservative Country anymore.