The right-leaning pollsters We Ask America have Pat Toomey with a 13-point lead over Joe Sestak (48-35), which would be the Republican's biggest lead thus far in the campaign. That said, the poll of 1,000 registered voters was done Aug. 4, has no crosstabs or other info, and has a 3% MoE.
The upshot from WAA:
Toomey’s lead is being fueled by a combination of an eight-point advantage among Independents and a sizable chunk of Democrats who are buying into his message. His ability to keep Sestak playing defense will undoubted be put to the test as the campaign progresses, though.