LANCASTER, Pa. -

Pennsylvania Governor Tom Corbett is falling further behind in his bid for re-election.

The Republican incumbent now has a mountain to climb before November, according to a new poll.

"He's got a Herculean task and if he wins he will make history," said Terry Madonna, a political pundit, who added Corbett is the most vulnerable incumbent governor.

A Franklin and Marshall College poll released Thursday showed Corbett's Democratic challenger, Tom Wolf, ahead by 25 points bringing in 49 percent of the vote to Corbett's 24 percent. Wolf's lead was slightly larger than the same poll in June.

"This race is 90 percent about Governor Corbett. He's the incumbent, it's about his record and has done nothing to give voters a reason to re-think his record," said Madonna. "He needs what we call a game change. I don't think you get into a panic, but I think you realize that you have to figure out a new approach."

The F&M poll also showed the majority of voters believe it is important for the next governor to make major changes to the state pension and income-tax systems.

Corbett released a new campaign ad Thursday taking jabs at Wolf. His campaign said the ad highlights Wolf's belief in reinstating Ed Rendell's tax-and-spend agenda and Wolf's support for President Obama's big government liberal agenda. It's been dubbed, "Threepeat."

Wolf has also fired off ads responding to the governor, and Madonna said to keep the lead he must avoid controversy.

"The last thing Tom Wolf wants is a rookie mistake so he needs to play it safe," said Madonna.

Madonna expects Corbett will close the gap a bit this fall, but in order to win he said his camp needs to regroup.