Bob Casey was endorsed over Ed Rendell in 2002. Arlen Specter was endorsed over Joe Sestak in 2010. State Rep. Scott Conklin wasn't endorsed for Lieutenant Governor in 2010, nor was Kathleen Kane for Attorney General in 2012. Primaries have a checkered recent history for endorsed candidates. There are advantages for being able to use the party's abilities, but in the end of the day, it just doesn't matter that much. If the people in that room all got up and went home and started knocking doors, that would change. There are some members though who just don't put in that level of work.
So I stay home. I probably shouldn't, in fact I shouldn't, but I do it anyway.