Are you saying the GOP's smear campaign against Lois Murphy is going to cancel out Gerlach's ties to Bush, Rendell's coattails, the DCCC's $3 million and Murphy's own warchest?
Look at 2004 - Higher turnout for the Dems (Presidential races always bring out more Dems than Gubernatorial races so don't use Rendell as if there will be a huge surge in turnout).
Murphy might have her personal warchest but Gerlach isn't too far behind.
First off, Bush is polling near 40%, not the low 30s. Secondly, midterms don't bring out as many Dems as Presidential races. Unless you are suggesting that this year's turnout will match a Presidential election's turnout, the point about Bush isn't that strong. Republicans might be frustrated with the President but not enough to turn away in huge droves from the more moderate Gerlach.
Lois Murphy is a nice person, but I'd vote for Gerlach in this race. I'd rather have a Republican whose forced to have a moderate voting record than an ex-head of a NARAL.
I believe the Presidential race two years ago helped Murphy a lot but I still don't fully understand how she could get so much support in a district like PA 6. The woman is outside of the mainstream in that area.