Casey runs well among independents, outpacing Smith 46 percent to 28 percent. Casey even has some support among Republicans, as 19 percent of GOP voters say they would vote for him over Smith. A virtual unknown before launching his Senate bid, Smith emerged from a crowded GOP primary field after spending $5 million of his own money on his campaign. He won the GOP nomination over businessman Steve Welch, who had received the endorsements of Republican Gov. Tom Corbett and the state party. Corbett's approval rating hit a new low in the poll. Forty-seven percent of Pennsylvania voters disapprove of the job the governor is doing, while 36 percent approve. The Quinnipiac University poll of 997 registered voters was conducted June 5 through June 10. It has a margin of error of plus or minus 3.1 percent.