Rasmussen's latest poll shows Santorum down 11 points an improvement of 4 pts from his poll in June. However, a new Morning Call/Muhlenberg poll apparently has Santorum pulling to within six points.

HARRISBURG -- Buoyed by a summer advertising blitz, U.S. Sen. Rick Santorum, R-Pa. has erased Bob Casey's broad lead in the battle for public opinion, closing to within a handful of points of the Democratic state treasurer, a new Morning Call/Muhlenberg College poll has found..... More critically for Santorum, whose views on abortion and other social issues tend to alienate moderate Republican voters, the percentage of voters who say they have a favorable opinion of him is increasing..... Look for complete results of the poll Sunday, exclusively in The Morning Call.

We'll see whether other polls show this kind of tightening (Zogby's last two Interactive polls pegged Casey's lead at seven and nine points), but if Casey loses his double-digit lead, pre-Labor Day, the conventional wisdom on this race (including RCP's) will have to change.