“Sen. Bob Casey is bracing for a GOP onslaught,” CNN reports. “After a summer where he and his GOP opponent, David McCormick, have engaged in a brutal exchange of attacks in the marquee US Senate race in Pennsylvania, leaving the race in a dead heat, Republicans are preparing to drop more than $100 million across the airwaves in the final two months of the campaign.” “The staggering sum, which accounts to roughly $40 million more than Casey and his allies are preparing so far, gives McCormick the biggest edge on the airwaves of any Senate candidate in the campaign’s home stretch.