Public education is the No. 1 issue in the poll, chosen by 29 percent of respondents, and also the main reason they gave for disappointment with Corbett.
Democrats have ripped Corbett for cutting more than $1 billion in state money for schools in his first budget in 2011.
Corbett says that the budget cut resulted from the expiration of federal stimulus money and that he has since increased state funding for education to the highest levels ever.
That is true if increases in contributions to the teachers' pension fund are counted, but that money does not show up directly in the classroom. Corbett's narrative of increased funding runs up against many people's experience of staffing and program cuts and higher property taxes across the state.
Corbett's ad push, costing an estimated $5 million since May, has not damaged Wolf much, the poll found.
The governor has run spots blasting Wolf for running a kitchen-cabinet company that is registered in Delaware, saying he is taking advantage of a loophole to avoid Pennsylvania corporate taxes - though he has offered no proof. Wolf and the company have denied using the loophole, but have declined to release corporate tax records that could rebut Corbett's assertions.
Other ads have seized on Wolf's desire to change the state's flat income tax so that wealthier taxpayers would pay more. Corbett's campaign argues that the Wolf plan could hike the tax burden for households earning more than $70,000 annually, which many consider a middle-class income.
Corbett campaign spokesman Billy Pitman noted that other polls based on likely voters have said the race is closer, and said the poll over-sampled Democrats.
"Regardless, the only poll that will matter is on Election Day, when we are confident Pennsylvanians will reelect Tom Corbett and [Lt. Gov.] Jim Cawley," Pitman said.
The poll is based on live telephone interviews with 520 registered Pennsylvania voters, conducted between Aug. 18 and Monday. Results are subject to a sampling-error margin of plus or minus 4.3 percentage points.
BY THE NUMBERS
Percentage points Gov. Corbett is behind Tom Wolf
Say Corbett deserves reelection
Say public education is top election issue